This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Twin Pregnancy, Molar Pregnancy, Gestational Trophoblastic disease and contraception in special situations (Sour Grapes!), Subject name: Gynaecology & Obstetrics
[{'content': 'Hydatidiform mole in USG appear as:- \nSelect and explain. \nA. Snowstorm pattern, B. Snow driven pattern, C. Cotton wool, D. Polka Dot sign', 'role': 'user'}, {'content': "Answer: A \nExplanation: USG showing snowstorm appearance of Hydatidiform mole Polka dot sign - Thickened trabeculae in a veebral body hemangioma, as seen on axial computed tomographic (CT) The cotton wool appearance - plain film sign of Paget's disease of bone Snow driven appearance - the calcifying epithelial odontogenic tumor (CEOT), also known as a Pindborg tumor", 'role': 'assistant'}]