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
Ghrelin is responsible for: 
Select and explain. 
A. Stimulation of appetite, B. Suppression of appetite, C. Stimulation of sleep, D. Suppression of sleep
A: Stimulation of appetite
Answer: A: Stimulation of appetite 
Explanation: Stimulation of appetite