This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics, Subject name: Medicine
[{'content': 'Most sensitive investigation for cystic fibrosis is? \nSelect and explain. \nA. CT scan, B. Ultrasound, C. Sweat electrolytes, D. Tomogram', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. (c) Sweat electrolytesRef: Harrison's Medicine 18th ed p 2149-50", 'role': 'assistant'}]