This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sexual offences, Subject name: Forensic Medicine
Which of the following tests is done for vaginal cells collected for the investigation for rape? 
Select and explain. 
A. Lugol's iodine test, B. Benzidine test, C. Takayama test, D. Florence test
A: Lugol's iodine test
Answer: A: Lugol's iodine test 
Explanation: Lugol's iodine test:- Lugol's iodine is applied on glans penis. If the person has done sexual intercourse, then a brown colour will occur due to reaction between Lugol's iodine and glycogen (present in vaginal epithelial cells, which get deposited on Glans penis during sexual intercourse). This test is positive up to 4th day of sexual intercourse