Shivering
Explanation: shivering action is an act to warm a homoeothermic body. Sweating makes the body cool, panting don’t keep body warm and dilating blood vessels does not keep body warm instead constriction of blood vessels is the initial process to conserve body heat followed by waves of muscle contraction, which is nothing but shivering. Alteration of the set point in torpor is also not the right answer
