In What Way, If Any, Is the Memory of Obsessive-Compulsive

In what way, if any, is the memory of obsessive-compulsive checkers unusual?

A) Their memory does not differ from that of normal people in any regard.
B) Their memory of what they have done is normal, but they do not trust their memory.
C) They cannot distinguish between what they have actually done and what they have only imagined doing.
D) Their memory is about normal, but they put more than the normal amount of confidence in their memory.