_____ provides energy for the brain during stress.

• A. Melatonin
• B. Thyroxin
• C. Cortisol
• D. Serotonin

Answer: (C)

Verified step by step guidance

1. Identify the context of the problem, which is about the physiological response of the brain during stress.
2. Understand that the question is asking for a substance that provides energy to the brain in stressful situations.
3. Recall that cortisol is a hormone released by the adrenal glands in response to stress and is known to help mobilize energy by increasing glucose availability in the bloodstream.
4. Differentiate between the options provided: Melatonin is related to sleep regulation, Thyroxin is involved in metabolism, and Serotonin is a neurotransmitter affecting mood.
5. Conclude that cortisol is the correct answer as it is directly involved in providing energy to the brain during stress by increasing glucose levels.