(d) All of the above

Explanation: The human brain is the command centre for the nervous system. The information is sent to the muscles after being taken from the sensory organs. The human brain structure is similar to the animal brain structure. Although it is larger than many mammals's brain structures, such as dolphins and elephants, It is a multifaceted organ controlling memory, thoughts, hunger, movement, blood circulation, and much more. Thus, the brain is responsible for balancing the body, regulating the heartbeat, and thinking.