<prompt> Hydrogenation of fatty acid is ?Hydrolysis by AlkaliAuto-oxidation of PUFAAddition of hydrogen to unsaturated fatty acidAddition of hydrogen to saturated fatty acid  <response>: Ans. is c i.e., Addition of hydrogen to unsaturated fatty acidAddition of hydrogen atoms to unsaturated fatty acid refers to hydrogenation. It reduces the number of double bonds in the unsaturated fats.Hydrogenation of unsaturated fats in the presence of a catalyst nickle in known as hardening, because it conves liquid vegetable oils into solid fats e.g. margarines, vegetable ghee, etc. 