This is a finding agreement across viewpoints question. Scientists 1 and 2 both propose "missing mass" (dark matter) to explain rotation curves, meaning they agree there's more mass than we can see. Scientist 3 explicitly states "There is no missing mass"—the discrepancy comes from wrong gravity laws, not hidden matter. Choice C (Scientists 1 and 2 only) is correct. Choice D incorrectly includes Scientist 3, who rejects the existence of missing mass. Pro tip: Carefully distinguish between agreeing about the problem (all three do) versus agreeing about the solution (additional mass vs. modified physics).

This is a comparing viewpoints question asking you to identify the core distinction between two hypotheses. Scientist 1 proposes WIMPs ("exotic new particle"), while Scientist 2 proposes MACHOs ("normal 'baryonic' matter"). The fundamental disagreement is about the TYPE of matter—exotic subatomic particles versus familiar objects like black holes and brown dwarfs. Choice A correctly captures this distinction. Choice B is wrong—both place dark matter in halos. Choice C is wrong—both accept Newtonian physics (only Scientist 3 rejects it). Choice D is wrong—both describe invisible/non-light-emitting matter. Pro tip: Focus on the fundamental disagreement, not superficial similarities.

Both scientists would agree that roots are essential for plant survival, despite disagreeing on the primary function. Scientist 1 'claims that the main function of roots in plants is nutrient absorption,' while Scientist 2 'argues it's stability and support.' Both viewpoints acknowledge that roots serve critical functions necessary for plant survival, whether nutritional or structural. The agreement is that roots play vital roles in plant biology, even though they emphasize different specific functions.

The statement that migration is mainly for breeding is consistent with Scientist 2's viewpoint but not Scientist 1's. Scientist 2 'argues it's for breeding purposes,' making reproduction the primary motivation for animal migration patterns. Scientist 1 'suggests that the primary reason for animal migration is seasonal food availability,' focusing on resource acquisition rather than reproduction. This represents Scientist 2's emphasis on reproductive behavior as the driving force behind migration.

Both scientists would agree that desertification is a complex issue, despite disagreeing on the primary cause. Scientist 1 'claims that the primary cause of desertification is overgrazing,' while Scientist 2 'argues it's climate change.' Both viewpoints acknowledge desertification as a significant environmental problem with serious consequences, even though they attribute different primary causes. The agreement is that desertification represents a major challenge requiring attention, regardless of the specific driving mechanism.

Scientist 1 focuses on sunlight as the primary factor for faster plant growth, while Scientist 2 emphasizes water supply as more critical. Scientist 1 hypothesizes that 'increased sunlight leads to faster growth due to enhanced photosynthesis,' directly linking sunlight to growth outcomes. Scientist 2 acknowledges that 'sunlight is important' but believes 'the water supply is a more critical factor,' shifting the emphasis to water availability. This represents a fundamental disagreement about which environmental factor has the greatest influence on plant growth rates.

The assumption that temperature gradients drive water movement underlies Scientist B's hypothesis about ocean currents. Scientist B 'argues that temperature differences are more significant' than wind patterns in influencing ocean currents. For temperature differences to drive currents, there must be an underlying assumption that these temperature gradients create density differences that cause water movement. Scientist A 'believes that ocean currents are primarily influenced by wind patterns,' focusing on atmospheric rather than thermal drivers.

Scientist 1 and Scientist 2 would most likely disagree on the primary cause of earthquakes. Scientist 1 'claims that earthquakes result from tectonic plate movements,' attributing seismic activity to geological plate interactions. Scientist 2 'argues they are caused by volcanic activity,' linking earthquakes to volcanic processes and magma movement. This represents a core disagreement about the dominant mechanism that generates earthquakes, whether it's plate tectonics or volcanic activity.

Both scientists would agree that human activities impact species survival, despite disagreeing on the specific mechanism. Scientist 1 'hypothesizes that the main driver of species extinction is habitat destruction,' while Scientist 2 'suggests climate change is more significant.' Both habitat destruction and climate change are consequences of human activities, so both scientists acknowledge human influence on extinction rates. The disagreement lies in which human-caused factor has the greater impact on species survival.

The assumption that urbanization directly increases pollution levels underlies Scientist 1's hypothesis. Scientist 1 'argues that increasing urbanization is the primary driver of air pollution,' which requires the assumption that urban development and growth directly lead to higher pollution concentrations. Scientist 2 'believes industrial activities are more critical,' focusing on manufacturing and production processes rather than urban development itself. For urbanization to be the primary driver, there must be a direct causal relationship between urban growth and pollution increase.