This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
[{'content': 'Phase-I participants are \nSelect and explain. \nA. Patients, B. Volunteers, C. Selected patients, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: (Volunteers)', 'role': 'assistant'}]