The option which would most likely result in the greatest decrease in the rate of a chemical reaction is adding an enzyme inhibitor to a reaction catalyzed by an enzyme. Enzyme inhibitor is known for slowing down any processes, especially when it comes to chemical reactions, so I'd say A is the correct answer.
The 2% of the insects will begin to reproduce and grow their population exponentially and in time enable the population to recover. This is if the population is large enough to enable random mating. The 98% reduction in population drastically reduces competition for the remaining individuals hence giving them abundant resources for them to thrive.
