Question

Which verb agrees in number with its subject?

Answer 1

Wrong. The correct answer is A. is. It is A because you are not talking about sequoias, you are talking about bark. Bark is singular as well as the word is. To make it easier, generalize what you are trying to say by taking sequoias out of the sentence. You wouldn't say, "The bark are sometimes two feet thick", would you? Are remains a plural state of being while is, is singular.

Answer 2

C. because the othe
r ones dont sound right
The bark of sequoias are sometimes two feet thick.