The chemical used in indelible ink (Election ink) is _____?
[A]Sodium Nitrate
[B]Potassium Nitrate
[C]Silver Nitrate
[D]Silver Iodide

Silver Nitrate
Indelible ink typically contain Silver Nitrate which stains the skin on exposure of ultraviolet light, leaving a mark that is impossible to wash off and is only removed on external skin cells are replaced.