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: Pharmacology
[{'content': 'Which of the following is an effect of grapefruit juice on drug metabolism ? \nSelect and explain. \nA. Enzyme inducer, B. Enzyme inhibitor, C. Inhibits tubular secretion, D. Inhibits tubular reabsorption', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Grapefruit juice contains furano cumarins and\xa0narangin that are CYP3A4 inhibitors.', 'role': 'assistant'}]