A Series of Enzymes Catalyze the Reactions Illustrated in the Following

Multiple Choice

A series of enzymes catalyze the reactions illustrated in the following metabolic pathway:
X → Y → Z → A.Product A binds to the enzyme that converts X to Y at a position remote from its active site.This binding of A decreases the activity of the enzyme that converts X to Y.What is substance X?

A) a coenzyme
B) an allosteric inhibitor
C) an intermediate
D) a substrate