This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urethra & Penis, Subject name: Surgery
Marion's disease is due to: 
Select and explain. 
A. Muscular hypertrophy of internal sphincter of urinary bladder, B. Fibrosis of the neck of bladder, C. Vesicular diverticula, D. Vesicular calculi
A: Muscular hypertrophy of internal sphincter of urinary bladder
Answer: A: Muscular hypertrophy of internal sphincter of urinary bladder 
Explanation: Ans. (a) Muscular hypertrophy of internal sphincter of urinary bladder* Congenital hypertrophy of the posterior urethra due to muscular hypertrophy and stenosis at bladder neck is known as Marion's disease.