TOEFL Reading: ETS-TOEFL阅读机经 - RDU8C7WQ535C5L9ML$

In paragraph 3 why does author discuss "honeybees warming their hives in response to an infestation by a fungal pathogen?" A. To give an example of how living in groups benefits animals B. To illustrate how social species combat parasites and disease C. To indicate that worker bees are the most active in fighting parasites and disease D. To demonstrate that avoiding a disadvantage of social living can carry its own costs