This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pharmacology, Subject name: Pharmacology
[{'content': 'ED50 is used for determining \nSelect and explain. \nA. Potency, B. Efficacy, C. Safety, D. Toxicity', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ed 50 measures potency Ld 50 measures safety or fatality ed50- dose required to produce 50% of the maximum effect LD50- The dose that causes death in 50 percent of the subjects tested Pgno-54 K D Tripathi Seventh edition', 'role': 'assistant'}]