Which Sentence Describes How the Metabolic Rate of an Endotherm

Which sentence describes how the metabolic rate of an endotherm compares with the metabolic rate of an ectotherm as the environment gets colder?

A) The metabolic rate in an endotherm goes down, while the metabolic rate of an ectotherm goes up.
B) The metabolic rate in an endotherm goes down, as well as the metabolic rate of an ectotherm.
C) The metabolic rate of an endotherm goes up, as well as the metabolic rate of an ectotherm.
D) The metabolic rate in an endotherm goes up, while the metabolic rate of an ectotherm goes down.