In 1960’s studies of rats, scientists found that crowding increases the number of attacks among the animals significantly. but in recent experiments in which rhesus monkeys were placed in crowded conditions, it was not such attacks that increased significantly, but rather instances of "coping" behavior, such as submissive gestures, avoidance of dominant individuals, and huddling with relatives. therefore the evidence from rhesus monkeys makes it doubtful that crowding significantly increases aggressive impulses in primates.
which of the following, if true, most seriously weakens the argument?
(a) the rhesus monkeys is the species of monkey that is more prone to fighting
(b) coping behavior was adopted by the crowded monkeys to forestall acts of aggression among them
(c) all the observed forms of coping behavior can be found among rhesus monkeys living in uncrowded conditions
(d) some individual monkeys in the experiment were involved in more attacks than the others
(e) some of the rhesus monkeys in the experiment were subjected to levels of crowding that are unlikely to occur in natural circumstances.