TOEFL Listening: TPO-TOEFL听力TPO - 9TV09RLYX490CR89R$

In the example the professor mentions, how do the ants benefit from their interaction with the caterpillars? A. The caterpillars protect the ants' eggs from predators. B. The caterpillars help the ants find a particular plant. C. The caterpillars produce a liquid to prevent ants from getting infections. D. The caterpillars produce a liquid from a species gland to feed the ants.