Why does it make sense to include temperature regulation in the same chapter as nutrition and digestion?

A)The rate of energy consumption is, in part, a function of body temperature.
B)Ectotherms receive most of their body heat from surroundings.
C)Ectothermy and endothermy are extremes of a continuum of thermoregulatory mechanisms.
D)Thermoregulation in ectotherms is energetically costly.