Pair-bonding in a population of prairie voles can be prevented by A) the ensuing confusion caused by introducing meadow voles. B) administering a drug that inhibits the brain receptor for vasopressin in the CNS of males. C) administering a drug that turns on ADH receptor sites in male voles. D) dying the coat color from brown to blond in either male or female prairie voles. E) allowing the population size to reach critically low levels.