This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors, Subject name: Pathology
[{'content': 'Which of the following is NOT a risk factor for endometrial carcinoma? \nSelect and explain. \nA. Obesity, B. Nulliparity, C. Smoking, D. Tamoxifen', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Endometrial carcinoma:- Type I Type II Age - 55-65 yr - 65-75 yr Finding -Endometrial Hyperplasia - Endometrial Atrophy Risk -E- Estrogen -N-Nulliparity -D-DM/Drugs(Tamoxifen) -O-Obesity - Atrophy - Thin Physique Behavior - Indolent - Spreads lymphatic - Aggressive - Intraperitoneal and lymphatic', 'role': 'assistant'}]