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: Radiology
[{'content': 'Most common method of radiation dose delivery is: \nSelect and explain. \nA. Teletherapy, B. Electron beam, C. Brachytherapy, D. Radio immunotherapy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Teletherapy REF: therapy, "External radiation therapy (also known as Teletherapy) is the most common kind of radiation therapy"', 'role': 'assistant'}]