Heterotherms Differ from Homotherms in That Only Heterotherms

Heterotherms differ from homotherms in that only heterotherms

A) can regulate their own body temperature.
B) are animals whose body temperatures are determined primarily by external sources of heat.
C) maintain a constant body temperature at all times despite changes in outside temperature.
D) always have a negative Q₁₀.
E) are animals that sometimes behave as an endotherm and at other times as an ectotherm.