This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cystic fibrosis & Sleep apnea, Subject name: Medicine
[{'content': 'The CFTR gene associated with cystic fibrosis is located on chromosome: \nSelect and explain. \nA. 4, B. 5, C. 7, D. 12', 'role': 'user'}, {'content': 'Answer: C \nExplanation: CFTR gene associated with cystic fibrosis is located on chromosome 7 In patients with cystic fibrosis blockage of the movement of ions and, therefore, water into and out of cells leads to the production of thick mucus. Absent vas deferens in males explains infeility in cystic fibrosis.', 'role': 'assistant'}]