Answer :
Answer:
Option B, an allosteric inhibitor.
Explanation:
As the enzyme activity decreases, it is not possible for A to be a coenzyme (most likely would increase the enzyme activity), a substrate (increases activity of enzyme by Le Chatler's principle) or an intermediate (no effect). A is unlikely to be a competitive inhibitor as this would not decrease the activity of the enzyme, only reduce the rate of conversion of substrate to product. A is most likely an allosteric inhibitor which binds to another site on the enzyme (other than the active site), resulting in a change in conformation of the enzyme which reduces the enzymatic activity.