This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Special topics, Subject name: Forensic Medicine
Colour of crystals in positive Florence test is - 
Select and explain. 
A. Yellow, B. White, C. Purple, D. Dark Brown
D: Dark Brown
Answer: D: Dark Brown 
Explanation: Ref:The essential of forensic medicine and toxicology Dr.K.S NARAYAN REDDY 32nd edition pg no 415 the stain is estracted by 10% HCL and a drop is placed on a glass slide and allow to dry a cover slip is place dover this , and a drop of florence solution(KI,iodide and water) this allowed to run under the cover slip .if the semen is present, dark brown crystals of choline iodide appeared immediately , they are rhombic or needle shaped crystals resembling haemin but are larger, arranged in clusters,rossettes, crosses etc... Choline orginate from the seminal vessicles,the test is not a proof of seminal fluid but only of presence of some vegetables or animal substances . a negative reaction is proof that the stain is not seminal