This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Human identification, Subject name: Forensic Medicine
Corneal tattooing may be done with: 
Select and explain. 
A. Gold chloride, B. Calcium chloride, C. Copper sulfate, D. Potassium permanganate
A: Gold chloride
Answer: A: Gold chloride 
Explanation: Cosmetic tattoos (also known as 'permanent makeup'): They camouflage skin discolorations, such as bihmarks (hemangiomas) or scars, tattooing'hair follicles' into bald areas or corneal tattooing in perforating injury. India ink is the most commonly used dye for corneal tattooing. Two other methods exist: chemical dyeing with gold or platinum chloride and carbon impregnation.