In which sentence does the verb agree with the subject?

A.

Island of the Blue Dolphins is based on a true story.

B.

Gulliver's Travels have been adapted for movies and television.

C.

A Tale of Two Cites are set in eighteenth-century Europe.

The sentence that the verb agrees with the subject is, option A. Island of the Dolphins is based on a true story. The subject of the sentence is "Island of the Dolpins" and the verb used is "is". A singular form of the verb is used because the subject is in a singular form too. The subject described by the verb is a title of a Novel.