Which if the following is not required by animals to control body temperature

The thing which is not required by animals to control body temperature is shown here: B. Animals must switch between ectotherm and endotherm methods. It is regulated by the hypothalamus that is responsible for reaction on changes of temperature. The hypothalamus stimulates sweat glands and body hair muscles in order to keep up the normal temperature so that the body would feel comfortable in both cold and hot conditions.