Answer: E) Predicate noun.
Explanation: A predicate noun is a single noun or a noun phrase that renames the subject of a sentence and follows a form of the verb "to be" or another linking verb. In the given sentence the linking verb is "to be" in the plural form of the present tense (are), and the noun that follows the verb is "courses" (because "elective" is an adjective), and it renames the subject "subjects" so the bolded word "courses" represents the predicate noun of the sentence.