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: Gynaecology & Obstetrics
[{'content': 'In postmenopausal women, RANK ligand expression is \nSelect and explain. \nA. Decreased, B. Increased, C. Same as pre-menopause, D. First decrease to increase later', 'role': 'user'}, {'content': 'Answer: B \nExplanation: In post menopausal women, decreased oestrogen levels lead to increased RANK ligand expression and decreased osteoprotegerin (OPG), resulting in bone resorption.', 'role': 'assistant'}]