Answer:
Glucose
Step-by-step explanation:
Because of the following factors, glucose serves as the brain's primary energy source. Glucose may be easily catabolized to provide energy to the brain since it cannot tolerate interruptions in energy flow. Since the brain cannot store calories, a quick supply of chemicals that can provide energy is essential for the brain's smooth operation. In this situation, blood can easily transfer glucose. Although fatty acids provide a source of energy for the rest of the body, they are unable to cross the blood-brain barrier because they are bound to blood albumin in blood plasma. These justifications explain why glucose serves as the brain's main source of energy. Ketone bodies could be the secondary source.