Which element is used to "paint" the skin to prevent infection from cuts and scratches

I would say the main element used to paint the skin to prevent infections from cuts and scratches is iodine. It is an antiseptic usually available in a solution of 2-7% elemental iodine together with potassium iodide and sodium iodide in an ethanol and water mixture, It has been used since 1908 in pre-operative skin preparation.

Ithink the answer is a or d.