This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'ACTH level is highest during: \nSelect and explain. \nA. Early morning, B. Evening, C. Afternoon, D. Night', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Early morningACTH level is highest during early morningQ. About 75% of daily output occurs between 4 AM and 10 AM.Secretion is least in the evening. The biological clock responsible for diurnal variation of ACTH is located in suprachiasmatic nuclei of hypothalamusQ.', 'role': 'assistant'}]