Sally Suffers from Trigeminal Neuralgia,a Painful Disease of the Trigeminal

Sally suffers from trigeminal neuralgia,a painful disease of the trigeminal nerve located in the face.She has undergone a surgical procedure whereby the trigeminal nerve was severed so that the pain signal would no longer be sent to the brain.Unfortunately,this worked for only a few months.Why was this not a permanent solution for Sally?

A) much of Sally's pain is psychological so cutting the nerve wouldn't help
B) the nerve can regenerate which enables pain to travel along a variety of pathways
C) it is very difficult to identify the trigeminal nerve during surgery
D) most of pain behaviour is learned and not dependent on the stimulus
E) Sally is still imagining her pain although it is really not there