This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
[{'content': 'The following adverse drug reaction seen in colonoscopy view is due to \nSelect and explain. \nA. Cascara, B. Bisacodyl, C. Castor oil, D. Loperamide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The picture shows Melanosis coli caused by Senna and cascara which are stimulant purgatives.bisacodyl usually cause hypokalemiaRef: KD Tripathi 7th ed pg 673', 'role': 'assistant'}]