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: Pathology
[{'content': 'Chance of having cystic fibrosis if only one parent is affected and other is normal \nSelect and explain. \nA. 25%, B. 50%, C. 70%, D. 80%', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., 50%", 'role': 'assistant'}]