This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
which of the following is false regarding SPARE RECEPTOR ? 
Select and explain. 
A. they are needed for binding drug to achieve the maximum effect, B. they respond to agonists only, C. they do not alter maximal efficacy, D. can be detected by finding that EC 50 < Kd for the agonist
A: they are needed for binding drug to achieve the maximum effect
Answer: A: they are needed for binding drug to achieve the maximum effect 
Explanation: SPARE RECEPTORS they are NOT needed for binding drug to achieve the maximum effect they respond to agonists only they do not alter maximal efficacy can be detected by finding that EC 50 < Kd for the agonist REF : KD TRIPATHI 8TH ED