D. a highly developed intelligence inhibits competitive action.

The author views higher or "detached" intelligence as a liability, placing people at a disadvantage: "It puts its possessor at a disadvantage in dealing with those whose intelligence faithfully serves their purpose by enabling them to scheme for their ends and to justify to themselves their desires. Such is the animal function of intelligence, and whenever it develops beyond this level, it inhibits rather than aids that effective action in the pursuit of natural ends which was the original function of the mind"