Hi MD Raihan Uddin,

This CR question is based on the concept of Representativeness - the idea that a small group can represent the larger whole.

The Facts:
-In studies from the 1960s, scientists found that CROWDING significantly increases the number of attacks among animals.
-In RECENT experiments, rhesus monkeys were placed in CROWDED conditions, but the number of attacks did NOT increase (there WAS an increase in "coping" behavior though).
-"Coping behavior" involves submissive gestures and avoidance of dominant individuals.

The Conclusion:
For ANY species of monkey, CROWDING is not likely to increase aggression in the same way that was seen in rats.

The Logic:
The author uses rhesus monkeys as representative of ALL monkeys. Since rhesus monkeys do NOT see an increase in the attacks when placed in CROWDED situations, the author concludes that ANY species of monkey will behave in the same way (and not in the way that rats behaved). Since this is a rather "loose" argument, to strengthen it, we need an answer that compares rhesus monkeys to other monkeys and provides some type of evidence that proves that rhesus monkeys behave in a way that is comparable to ALL monkeys.

Answer C gives us that comparison AND tells us how rhesus monkeys are MORE aggressive than other monkeys. This tells us that other monkeys are even less aggressive - since the rhesus monkeys didn't attack one another, other monkeys would be even less likely to attack one another when placed in a crowded situation.

GMAT assassins aren't born, they're made,
Rich