This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
Which of the following drug is used for overactive bladder? 
Select and explain. 
A. Duloxetine, B. Darifenacin, C. Oxybutynin, D. Flavoxate
B: Darifenacin
Answer: B: Darifenacin 
Explanation: Ref:KD Tripathi pharmacology 7th edition (page.no: 118) Darifenacin & Solifenacin are competitive muscarinic receptor antagonists of the M3 muscarinic receptor of the bladder. Receptor blocking limits bladder contractions, and reduce symptoms of bladder irritability/overactivity