This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Pharmacology
With which of the following receptors theophylline has an antagonist interaction? 
Select and explain. 
A. Histamine receptor, B. Bradykinin receptor, C. Adenoside receptor, D. Inidazoline receptor
C: Adenoside receptor
Answer: C: Adenoside receptor 
Explanation: theophylline is an eg of methylxanthine the action of this identified as a) release of ca from sarcoplasmic reticulum b) inhibition of phosphodiesterase c)blockade of adenosine receptor ESSENTIALS OF MEDICAL PHARMACOLOGY SEVENTH EDITION KD TRIPATHI PG NO.226