One Reason Why the Checking Rituals of Obsessive-Compulsive People May

One reason why the checking rituals of obsessive-compulsive people may last so long and give so little relief is that such people

A) are generally far below normal in their intelligence.
B) receive praise and other reinforcement for engaging in these rituals.
C) are very easily distracted from what they intend to do.
D) do not trust their memory of whether they have completed the ritual.