Choose the correct sentence.

A) The fee for various classes are different.
B) The fee for various classes is different.
Answered A

the answer is B

reason why is because if we get rid of "for various classes" which is a prepositional phrase so we do not need it for these grammar problems, we get the fee is/are different. Thus, since fee is singular, we get B or the fee for various class is different. (I know why you answered A, its very tricky. You think because classes is plural so the whole thing is, but classes is part of the prepositional phrase so "fee" is the noun)