Mussels and Sponges Sometimes Contain Methanotrophs as Intracellular Symbionts Because

Mussels and sponges sometimes contain methanotrophs as intracellular symbionts because the methanotrophs

A) remove otherwise toxic levels of methane from the environment.
B) convert methane to carbohydrate for use by the host.
C) allow the partnership to use hydrogen sulfide as a source of electrons.
D) all of the choices