Which of the following is not required by animals to control body temperature?
a. animals must find a source of heat.
b. animals must switch between ectotherm and endotherm methods.
c. animals must be able to conserve heat when temperatures drop.
d. animals must be able to get rid of excess heat when temperatures increase.

B. Animals must switch between ectotherm and endotherm methods.

The hypothalamus in the brain, is responsible for monitoring the body temperature. The hypothalamus causes the body to react differently when the body is too hot or if the temperature gets too cold. The normal body temperature is 37'. The hypothalamus triggers the receptors such as sweat glands and body hair muscles in the body.The sweat glands open up when the body is too hot and secrets sweat until the temperature is regulated again. Similarly in cold conditions the body hair muscles pull the hair upright because standing hair absorbs more heat until the falling body temperature returns to normal.

The answer is observations and interpreting.