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: Forensic Medicine
Following is used to document tear of hymen in a victim of rape: AI 12; NEET 15 
Select and explain. 
A. Vaginal speculum, B. Glaister-keen rod, C. Cylinder rod, D. Hegar's rod
B: Glaister-keen rod
Answer: B: Glaister-keen rod 
Explanation: Ans. Glaister-keen rod