Answer:
The correct answer would be an option 4.
Feedback inhibition is the phenomenon by which key enzymes of a metabolic pathway are inhibited by the end product of the pathway.
A metabolic pathway is usually a multi-step process in which numerous enzymes are involved.
When the end product of the pathway is present in high concentration, it results in the inhibition of the first committed step (first irreversible step) of the pathway.
For example, an excess of ATP in a cell inhibits some of the enzymes associated with cellular respiration in order to prevent further synthesis of ATP.
