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
What is the root value of the posterior cutaneous nerve of the thigh? 
Select and explain. 
A. S1, S2, B. S1, S2, S3, C. S2, S3, D. S2, S3, S4
B: S1, S2, S3
Answer: B: S1, S2, S3 
Explanation: Posterior cutaneous nerve of thigh- S1,2,3