In Each of the Following Sets, Select the Sentence That

Multiple Choice

In each of the following sets, select the sentence that uses the correct coordinating or subordinating conjunction and that is punctuated correctly. Which sentence uses the correct coordinating or subordinating conjunction and is punctuated correctly?

A) If he doesn't call by 5 p.m. then: I'll have to give the concert tickets to someone else.
B) If he doesn't call by 5 p.m., then I'll have to give the concert tickets to someone else.
C) If he doesnt call by 5 p.m. then Ill have to give the concert tickets to someone else.