Researchers Measure Animals' Oxygen Consumption (VO₂) as a Way to Quantify

Researchers measure animals' oxygen consumption (VO₂) as a way to quantify metabolic rate. A researcher measured the VO₂ for two animals, A and B, as function of ambient temperature and collected the data shown in Figure 32.2 below. One of the animals was an ectotherm and one was an endotherm. Which animal was the endotherm and why?

A) Animal A is the endotherm because at colder temperatures endotherms need to warm themselves through their own metabolic activity, which is supported by the data.
B) Animal A is the endotherm because endotherms do not need to regulate their own body temperature by changing metabolic activity, which is supported by the data.
C) Animal B is the endotherm because at colder temperatures endotherms need to warm themselves through their own metabolic activity, which is supported by the data.
D) Animal B is the endotherm because endotherms do not need to regulate their own body temperature by changing metabolic activity, which is supported by the data.