The answer will obviously be letter A
Competitive inhibition vs allosteric inhibition
In competitive the substrate and inhibitor bind at the same active site - pretty straightforward. In allosteric regulation (speaking specifically about inhibition here), the inhibitor is binding at a site other than the active site, and changing the enzyme in some way to make it inactive.
Answer;
The first choice (A) is an unsaturated fatty acid.
Explanation;
-An unsaturated fat is a fat or fatty acid in which there is one or more double bond in the fatty acid chain.
-A fat molecule is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond. In this case, the unsaturated fat (A) is polyunsaturated.