This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal tract, Subject name: Pharmacology
[{'content': 'Which of the following is the most common adverse effect of omeprazole \nSelect and explain. \nA. Nausea, B. Constipation, C. Jaundice, D. Black stools', 'role': 'user'}, {'content': 'Answer: A \nExplanation: PROTON PUMP INHIBITORS (PPIs) Omeprazole Adverse effects:- Nausea, loose stools, headache, abdominal pain, muscle and joint pain, dizziness, Rashes. Leucopenia and hepatic dysfunction are infrequent. On prolonged treatment atrophic gastritis has been repoed. Ref:- kd tripathi; pg num:- 653', 'role': 'assistant'}]