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
What is the type of Antagonism when 2 different drugs act on 2 different sites on the same cell and their response is opposite to each other ? 
Select and explain. 
A. Chemical antagonism, B. Physiological antagonism, C. Competitive antagonism, D. Reversible antagonism
B: Physiological antagonism
Answer: B: Physiological antagonism 
Explanation: Physiological antagonism - 2 different chemicals acting on different sites of the same cell and resulting in opposite response in its pharmacological effect is termed as Physiological antagonism. e.g Histamine acting on H1 receptors causes Bronchoconstriction while Adrenaline acting on Beta 2 receptors causes Bronchodilation. Both these receptors are present on bronchial smooth muscles but produce opposite response to each other.