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 one of the following statements about influence of smoking on risk of coronary hea disease (CHD) is not true? \nSelect and explain. \nA. Influence of smoking is independent of the risk factors for CHD, B. Influence of smoking is only additive to other factors for CHD, C. Influence of smoking is synergistic to other risk factors for CHD, D. Influence of smoking is directly related to number of cigarettes smoke per day', 'role': 'user'}, {'content': 'Answer: C \nExplanation: There is evidence that influence smoking not only independent of but also synergistic with other risk factors such as hypeension and elevated serum cholesterol. This means that the effect are more than additive. Ref-Park&;s textbook of Preventive and Social Medicine 24th edition. *', 'role': 'assistant'}]