This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharmacodynamics, Subject name: Pharmacology
[{'content': 'In sub-acute toxicity studies, the drug is given to animals for \nSelect and explain. \nA. Single dose, B. 2-12 weeks, C. 6-12 months, D. 1-3 years', 'role': 'user'}, {'content': 'Answer: B \nExplanation: PRECLINICAL TOXICITY STUDIES Acute toxicity studies Single escalating doses are given to small group of animals and the animals are observed for 1-3 days. LD50 is calculated. Organ toxicity is examined by histopathology. Sub-acute toxicity studies Repeated doses of the drug are given for 2-12 weeks. Animal are examined for ove effects, food intake, body weight, hematology Chronic toxicity studies The drug is given for 6-12 months. Animal are examined for ove effects, food intake, body weight, hematology', 'role': 'assistant'}]