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
The dose of a drug required to produce a specified effect in 50% of the population is 
Select and explain. 
A. Ld50, B. Td50, C. Md50, D. Ed50
D: Ed50
Answer: D: Ed50 
Explanation: None