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
Which of the following drug has maximum risk of dry mouth: 
Select and explain. 
A. oxybutynin, B. Trospium., C. Solefancin., D. Flavoxate.
A: oxybutynin
Answer: A: oxybutynin 
Explanation: None