Right choice is (d) Boiling 65% nitric acid is used as a corrosive solution and used to evaluate the heat treatment of stainless steels
For explanation I would say: The Huey test is used to check the heat treatment of stainless steels. It uses boiling 65% nitric acid as a corrosive solution. Stainless steel is an alloy of iron, carbon, chromium, and nickel.