Answer: Choice C
Reason:
The center of dilation is point A, which means this point will not move. It's the only fixed point. The other points will move closer to point A.
Because of this, we rule out choice A and choice D.
The answer is between choice B and choice C.
But we can rule out choice B since segment AB' has length less than 3/4 of segment AB.
AB' < (3/4)*AB
Notice how B' is past the midway point from A to B. We need B' to be on the other side of the midpoint.