Which sentence uses a verb that agrees with its compound subject?
a. a robin and a sparrow has eaten from the bird feeder.
b. either mario or larry are a nominee for the award.
c. either those leftovers or the trashcan are causing that smell.
d. neither my aunts nor my uncles have arrived yet.

The correct answer is C because it is the only option where a verb agrees with its compound subject correctly.
In A, it should be 'have eaten', because there are two subjects, 'a robin' and 'a sparrow'.
In B it should be 'are nominees', because there are two of them.
In D, neither goes with a singular verb. 

Look at the passages where the author describes the isolation and insanity that dr frankenstein has