Which is a true statement about the nominative case?

a. a pronoun comes before a noun to show ownership.

b. a pronoun can be used as the preposition of a verb.

c. a pronoun can be used as the subject of a verb.

Nominative case pronouns are pronouns that are used as subjects in the sentence. Such pronouns include I, he, she, it, they, you and we. Based on the statements above, the one that is true about nominative case is that, it is a pronoun that can function as the verb's subject. It would be option C.