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: Anatomy
A patient with external hemorrhoids develops pain while passing stools. The nerve mediating this pain is - 
Select and explain. 
A. Hypogastric nerve, B. Pudendal nerve, C. Splachnic visceral nerve, D. Sympathetic plexus
B: Pudendal nerve
Answer: B: Pudendal nerve 
Explanation: External piles (hemorrhoids) lie below the pectinate line and are therefore painful.
Pain sensation below the pectinate line is carried by inferior rectal nerve, a branch of the pudendal nerve.