The correct answer is: A: president. Predicate nominative (also called predicate noun) is a word in sentence which completes a linking verb and renames the subject. The examples of linking verbs are: is, are, was, am, were, be, being (the helping verb); look, smell, taste, touch, sound (the sense verbs); and there are also verbs like: seem, appear, become, stay, turn, etc. The verb with the predicate nominative can always be replaced with "equals". Example: Mr. Robinson is professor. Professor is predicate nominative, and the sentence would mean the same, if it was written like this: Mr. Robinson equals professor.
