Question

Which verb best completes the sentence?

Some of the students ________ applying to out-of-state colleges.

A.
have been

B.
had

C.
has been

Answer 1

Some of the students have been applying to out-of-state colleges.

It cannot be 'had' because it says applying. 
It cannot be 'has been' either because it says Some of the students. (Has doesn't match plural verbs)