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: Unknown
[{'content': 'The least amount of fetal Rh+ve blood needed to cause isoimmunization in a Rh negative mother is - \nSelect and explain. \nA. 0.1 ml, B. 0.01 ml, C. 0.001 ml, D. 10 ml', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: A', 'role': 'assistant'}]