Read the passage and answer the question.
In climate policy, carbon pricing is often presented as a single instrument that can replace most other interventions. By putting a cost on emissions, the argument goes, markets will find the cheapest reductions. Pricing can indeed encourage efficiency and innovation, but it does not automatically address every barrier to decarbonization. Some sectors face coordination problems—such as building charging networks—that require collective investment. Others involve long-lived infrastructure, where decisions made today lock in emissions for decades and where price signals may be too weak or too uncertain to shift behavior quickly. Additionally, political constraints can lead to prices that are lower than what models recommend, limiting impact. For these reasons, many analysts favor policy packages: carbon pricing combined with standards, public investment, and research support. The question is not whether pricing "works," but what complementary measures are needed for it to work at the scale and speed required.
Which of the following best describes the main idea of the passage?
- To argue that carbon pricing is unnecessary because voluntary corporate action will solve climate change
- To explain that while carbon pricing is useful, it is not sufficient by itself and should be part of a broader policy package (correct answer)
- To provide a detailed comparison of different carbon tax rates used in various countries over time
- To discuss climate policy in general without taking a position on carbon pricing
- To claim that markets always reduce emissions optimally once any price is introduced, making other policies harmful
Explanation: This question tests the main idea of the passage by seeking its best description. A correct main idea answer should address the usefulness and limitations of pricing, advocating complements. The passage develops this by noting pricing's efficiency but barriers like coordination, with examples of sectors. It favors packages with standards and investments for scale. Choice B justifies this as the central idea, emphasizing insufficiency and broader policies. In contrast, choice A is a distractor that misrepresents by claiming pricing unnecessary, contradicting the passage's support. Choice E fails by overstating market optimality, ignoring the need for complements.