The enzyme atcase (aspartate transcarbamoylase) catalyzes the first step in the multi-step synthesis of pyrimidine (single ring) nucleotides. ctp, a pyrimidine, is an inhibitor of atcase. this is an example of competitive inhibition feedback inhibition

Feedback inhibition

Explanation:

Feedback inhibition is one of the mechanisms that regulate the activities of enzymes. In feedback inhibition, accumulation of the product of a multistep metabolic pathway inhibits the enzyme of the first reaction of the metabolic pathway. Aspartate transcarbamoylase is an allosteric enzyme and catalyzes the formation of N-Carbamoylaspartate from aspartate. The enzyme is inhibited as the end product of the pathway, that is, CTP (Cytidine 5'-triphosphate) is accumulated in cells. This is also called end-product inhibition.

it's c. (to reduce the greenhouse effect/carbon gasses)