The correct option to regulate body temperature is option 2 - Hypothalamus. The hypothalamus is a small region in the brain that plays a crucial role in regulating various bodily functions, including body temperature. It acts as a thermostat to maintain a stable internal temperature, referred to as homeostasis.

The hypothalamus receives information about the body`s temperature from temperature receptors located throughout the body. If the body temperature deviates from the set point, the hypothalamus sends signals to different parts of the body to initiate responses that bring the temperature back to normal. For example, if the body is too hot, the hypothalamus triggers sweating to cool down the body. If the body is too cold, the hypothalamus initiates shivering to generate heat.

Alert - correct answer should be 1- Hypothalamus