The enzyme fumarase catalyzes the reversible hydration of fumaric acid to l-malate, but it will not catalyze the hydration of maleic acid, the cis isomer of fumaric acid. This is an example of: A. biological activity. B. chiral activity. C. racemization. D. stereoisomerization. E. stereospecificity.

This is an example of E. stereospecificity.

Explanation:

We talk about a stereospecific reaction when sterechemically different reagents react differently. Fumarase is an enzyme that catalyzes the reversible transformation of fumarate into malate by hydration. Human enzymes are specific for L-amino acids and D-carbohydrates, the enzyme fumarase is an example of stereospecificity since it hydrates the fumaric acid (trans form) to maleic acid, but does not act on the corresponding cis form, the maleic acid, that is, fumarase introduces a molecule of water into fumaric acid, but the cis isomer, that is, maleic acid, is not attacked.