Answer:
Hey!
Your answer is A. Continental crust is pulled apart at a divergent boundary.
Step-by-step explanation:
A rift basically is another word for MOVING APART...at divergent boundaries the plates MOVE APART...
Sometimes in this case, the part of land on the boundary can sink into the space created by the parting...this is what we see in the East African Rift Valley (and the whole valley in general!).
I HOPE THIS HELPED YOU!