A) the decision faced by aphids taken captive by slave-making ants over whether to escape or to cooperate with the ants. B) a model of decisions regarding defection or cooperation with another individual. C) reproductive decisions faced by animals at the edge of their species' range regarding whether to hybridize with another species or continue searching for a member of their own. D) "buyer's remorse" by a member of a mated pair, wishing to choose a different mate but facing the high costs of searching.