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
Grey powder (chalk + mercury) is used in ? 
Select and explain. 
A. Poroscopy, B. Cheiloscopy, C. Dactylography, D. Palato prints
C: Dactylography
Answer: C: Dactylography 
Explanation: Ans. is 'c' i.e., Dactylography A latent finger print may be developed by dusting the area with coloured powders to provide a contrast, and its pattern is recorded by photography. It can also be examined by oblique lighting. The commonly used powder is 'grey' powder (chalk and mercury), but white powders (lead carbonate or French chalk) are used for dusting dark surfaces.