Concentration Changes Over Time Practice Test

A reactant $A$ is consumed in the reaction $A \rightarrow$ products. Five concentration–time curves (Curves 1–5) are shown for $A$ under different conditions. Each curve levels off when the reaction is complete. Which curve shows a reaction that maintains a relatively high rate for longer (i.e., stays steep for a longer time before gradually leveling off)?

A student runs five trials of the same reaction and plots $A$ versus time (Curves 1–5). Each curve shows $A$ decreasing and then leveling off when the reaction is complete. Which curve most strongly suggests an initial delay (very small change at first) followed by a faster consumption of $A$ later?