Passage Summary: Ants are usually very aggressive toward intruders, but they tolerate certain caterpillars that provide them with food, even though those caterpillars are hunted by the very wasps the ants fight off.

Reasoning: Ants protect their territory from invaders like wasps; riodinid caterpillars provide food for ants; wasps are predators of these caterpillars; ants do not attack these caterpillars.

Analysis: We are looking for a statement that must be true based on the interaction of these facts. Since ants attack wasps (the predators of the caterpillars) and the ants benefit from the caterpillars' secretions, the ants' defensive behavior likely serves as a protective shield for the caterpillars. Look for an answer that synthesizes the relationship between the ants' aggression toward wasps and the survival of the food-providing caterpillars.