Select the sentence which is correctly punctuated:

A) He has 2 major hurdles to accomplish before becoming a doctor: completing his residency
and passing the state exam.
B) He has 2 major hurdles to accomplish before becoming a doctor; completing his residency
and passing the state exam.
C) He has 2 major hurdles to accomplish before becoming a doctor, completing his residency
and passing the state exam.
I answered C, but second guess myself because of A

I just want to check on this one too, please and thanks:)

Many words in English are both subjects and verbs:
A) False
B) True
My answer is B