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: Radiology
[{'content': 'Gestation sac is picked up by USG earliest at \nSelect and explain. \nA. 5 - 6 weeks of gestation, B. 6 - 8 weeks of gestation, C. 8 - 10 weeks of gestation, D. 12 weeks of gestation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Earliest by 4 1/2 weeks of gestation.', 'role': 'assistant'}]