You've Discovered an Enzyme That Can Catalyze Two Different Chemical

You've discovered an enzyme that can catalyze two different chemical reactions.Which of the following is most likely to be correct?

A) The enzyme contains both α-helices and β-pleated sheets.
B) The enzyme is subject to both competitive inhibition and allosteric regulation.
C) Two types of allosteric regulation occur-the binding of one molecule activates the enzyme,while the binding of a different molecule inhibits it.
D) Either the enzyme has two distinct active sites,or the reactants involved in the two reactions are very similar in size and shape.