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: Radiology
Least sensitive structure to radiation is: 
Select and explain. 
A. Uterus, B. Cervix, C. GIT, D. Vagina
D: Vagina
Answer: D: Vagina 
Explanation: Ans. Vagina