Answer:
C. He didn't hear the doorbell - broken since last week - when the delivery person arrived.
Step-by-step explanation:
If you are going to use the dash, you use it as a break in a sentence, or as a sort of connection between two words. (like door-salesperson) to draw a stronger connection between the two. In this case, option C is the correct answer, as the break in the sentence makes sense if said aloud.