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 terms best describes a drug that blocks the action of adrenaline at its receptors by occupying those receptors without activating them ? \nSelect and explain. \nA. Pharmacologic antagonist, B. Non competitive antagonist, C. Physiologic antagonist, D. Chemical antagonist', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]