Imagine That You Are Participating in a Friend's Psychology Experiment

Imagine that you are participating in a friend's psychology experiment. She asks you to close your eyes and hold out your finger. She tells you that she will prick your finger with a needle in the same place several times and then will start to prick other places. Your task is to tell her when you first feel the pin prick in a different place. She then repeats the same process but starts on your back. You might predict that the distance at which you could first detect a pin prick in a new location would be:

A) much smaller on the finger than the back
B) much smaller on the back than the finger
C) approximately equal in the two places
D) a little bit smaller on the finger than the back