The Larvae of Stream Caddisflies Graze on Algae in Streams

The larvae of stream caddisflies graze on algae in streams and defend territories from other individuals. A researcher observed that in streams with low algae abundance, caddisflies tended to defend large territories, while in streams with high algae abundance, individuals tended to defend small territories. Territory size was intermediate in streams with moderate levels of algae. What can you conclude from these data?

A) Territoriality in this species functions to prevent starvation
B) Caddisfly size affects territory size
C) Algae abundance affects territory size in caddisflies
D) The environment affects territory size in caddisflies
E) Algae abundance is correlated with territory size in caddisflies