Final answer:
The brain uses the majority of its energy for cognitive processes and information processing in the cerebral cortex, as well as maintaining autonomic processes like respiration and heartbeat, rather than producing hormones, controlling reflexes, or storing memories exclusively.
Step-by-step explanation:
The question asks about the primary use of energy by the brain. Notably, the brain is a highly energy-intensive organ, utilizing roughly 20% of the body's energy, most of which is in the form of glucose. The brain has multiple functions, including controlling mental processes like reasoning, imagination, memory, and language, as well as interpreting sensory information and commanding bodily responses.
The brain also takes on critical roles in maintaining autonomic processes that regulate essential body functions, such as respiration and heart rate. It is involved in controlling voluntary movements and muscle coordination via the cerebellum and brainstem, but the largest chunk of energy that the brain uses is dedicated to the cerebral cortex for numerous cognitive processes and information processing.
While producing hormones is indeed a function related to the brain through the hypothalamus and pituitary gland, it is not the main energy expenditure. Reflexes are controlled by the brain and the spinal cord but also do not constitute the majority of the brain's energy usage. Storing memories does use energy, but not to the degree that routine information processing and maintenance of basic functions do.