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': 'According to Heel effect: \nSelect and explain. \nA. High intensity x-rays are found at cathode., B. Low intensity x-rays are found at anode., C. Both of the above., D. None.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: According to “Heel effect”,\xa0when cathode rays strike anode target, X-rays\xa0with high intensity are found towards cathode side of central ray and X-rays with low intensity are found towards anode. This is due to self absorption of photons in the anode target.', 'role': 'assistant'}]