This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fundamentals in Radiology, Subject name: Radiology
[{'content': 'Maximum scattering in X-ray plate occurs in \nSelect and explain. \nA. Carbon, B. Mercury, C. H+, D. Ca++', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Scattering is directly propoional to the number of electrons available in the outer shell of the atom. option A : Carbon has 4 outer shell electrons option B : mercury has 2 outer shell electrons option C : H+ has 0 outer shell electrons option D : Ca++ has 0 outer shell electrons', 'role': 'assistant'}]