I would say C is the correct answer
She does not believe what her grandfather has told her.
A word in the nominative case that completes a copulative verb, such as son in the sentence Charlie is my son.
Portia is the romantic heroine of The Merchant of Venice, William Shakespeare's tragicomedy. When Portia's favorite suitor, BASSANIO, wins a contest devised by her father, they marry, and Portia gives her new husband a ring he promises to wear forever.