The Fact That Dirt and Contamination Were Threats to Our

The fact that dirt and contamination were threats to our ancestors suggests

A) that preparedness theory may help explain obsessive-compulsive disorder.
B) that fear of these things is rational.
C) that obsessive-compulsive disorder probably exists in many species, not just humans.
D) that obsessive-compulsive disorder is one of the oldest disorders in existence.