Oils on treating with hydrogen in the presence of nickel catalyst form fats. This is an example of
(d) addition reaction
Explanation with the correct answer: When Vegetable oil is treated with dihydrogen in the presence of Nickel as a catalyst we get saturated hydrocarbon. This is an example of addition reaction as hydrogen is added in vegetable oil to get vegetable ghee. Therefore, option (d) is the correct answer.
Explanations for incorrect answer:
Option (a) - The reaction in which oxygen combines with other elements or compounds is called as an oxidation reaction. Therefore it is incorrect.
Option (b) - A displacement reaction is the one wherein the atom or a set of atoms is displaced by another atom in a molecule. Therefore it is an incorrect answer.
Option (c) - Substitution reaction is defined as an element in which a group of one element is replaced by another element. Therefore it is an incorrect answer.