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': 'Which of the following is true of paralleling cone\ntechnique \nSelect and explain. \nA. The radioopacity of the zygoma is superimposed on the roots of third molars, B. Easy to place with the film holder, C. Less of gag reflex, D. No need to sterilize the film holder', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]