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
Drug efficacy refers to: 
Select and explain. 
A. Effectiveness of drug in life threatening conditions, B. The maximal intensity of response that can be produced by the drug, C. The dose of the drug needed to produce half maximal effect, D. The minimum dose of the drug needed to produce toxic effect
B: The maximal intensity of response that can be produced by the drug
Answer: B: The maximal intensity of response that can be produced by the drug 
Explanation: None