Why Was It Informative for Researchers to Study the Proximate

Why was it informative for researchers to study the proximate causation of Daphnia switching reproductive tactics in the laboratory?

A) Daphnia in the wild were genetically identical and the laboratory was the only place where Daphnia would reproduce sexually.
B) Daphnia could not obtain enough energy in the wild to reproduce sexually.
C) Multiple proximate factors were leading the reproductive switching tactics and it is simpler to tease these factors apart in the lab where a researcher can run controlled experiments.
D) Daphnia were never under high crowding conditions in the wild.