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: Physiology
[{'content': 'Most potent vasopresser is: \nSelect and explain. \nA. Angiotensin II, B. Renin., C. Aldosterone., D. Cortisole', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ganong 22 –456\nAngiotensin I appears to function solely as the precursor of angiotensin II does not have any other established action. Angiotensin II- previously called hypertension or angiotonin- produces arteriolar constriction and a rise in systolic and diastolic blood pressure. It is one of the most potent vasoconstrictors known, being four to eight times as active as norepinephrine.', 'role': 'assistant'}]