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': 'Granisetron, has antiemetic properties because of: \nSelect and explain. \nA. Dopaminergic receptor — blocking actions, B. Gabamimetic actions, C. Gaba-inhibitory actions, D. Serotonin receptor-blocking action', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Granisetron is 5-HT3 antagonist and is\xa010 times more potent than ondansetron, and probably\xa0more effective during the\xa0repeat\xa0cycle\xa0of chemotherapy.\xa0The\xa0weak 5-HT4 blockade\xa0seen\xa0with\xa0ondansetron\xa0 has\xa0not been\xa0detected\xa0in\xa0granisetron. lts\xa0plasma\xa0t½\xa0is longer\xa0(8-12\xa0hrs)\xa0and\xa0it\xa0needs\xa0to\xa0be\xa0given only\xa0twice\xa0on\xa0the\xa0day\xa0of chemotherapy.', 'role': 'assistant'}]