Hello! Your answer would be C, They regulate body temperature through behavioral mechanisms.
An endothermic animal is one which is capable of maintaining its own body temperature. They do this through physiological mechanisms, which is what the last choice is saying - these involve things such as hormones, sweating, etc.
These endothermic animals are considered warm blooded. This is because they can make their own body heat. Humans and other mammals are endothermic. We generate our own heat - we don't rely on sunbathing or shade to cool down or heat up our <u>internal</u> body temperature.
Hope this helps!
