This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Which of the following is a nonmodifiable risk factor for coronary hea disease? \nSelect and explain. \nA. Cigarette smoking, B. Elevated serum cholesterol, C. Alcoholism, D. Age', 'role': 'user'}, {'content': "Answer: D \nExplanation: park's textbook of preventive and social medicine 23rd edition. *non modifiable risk factors for CHD :age,sex,ethnicity, genetic factors. *modifiable risk factors: obesity,alcohol,physical activity, saturated fat, socio-economic status.", 'role': 'assistant'}]