The brain is located inside the head and is responsible for controlling what the body does. It is the central organ of the nervous system and plays a crucial role in processing information, coordinating movements, regulating bodily functions, and controlling behavior. The brain receives and interprets signals from the senses, allowing us to perceive and interact with the world around us. It also controls vital functions such as breathing, heart rate, and digestion. Therefore, the brain is the correct answer as it is the main control center of the body.