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
True statement about the upper half of anal canal is - 
Select and explain. 
A. Insensitive to pain, B. Drained by superficial inguinal lymph node, C. Lined by squamous epithelium, D. Supplied by superior mesenteric artery
A: Insensitive to pain
Answer: A: Insensitive to pain 
Explanation: Upper part of anal canal above pectinate line is supplied by autonomic nerves and is therefore insensitive to pain.
Upper part of anal canal above pectinate line is drained by inferior mesenteric node (into internal iliac nodes), lined by columnar epithelium and is supplied by superior rectal artery (Continuation of inferior mesenteric artery).