The correct answer is (c) Hydrogen.
Hydrogen is used in the manufacture of Vanaspati from vegetable oil because it is a reducing agent. This means that it can remove oxygen from the vegetable oil, which makes it more stable and less likely to go rancid. Hydrogen is also a good solvent, which means that it can help to break down the vegetable oil into smaller molecules. This makes it easier to process and to remove any impurities.
Oxygen is not used in the manufacture of Vanaspati because it is an oxidizing agent. This means that it can add oxygen to the vegetable oil, which makes it more unstable and more likely to go rancid. Nitrogen is not used in the manufacture of Vanaspati because it is a non-reactive gas. This means that it does not have any effect on the vegetable oil. Carbon dioxide is not used in the manufacture of Vanaspati because it is a waste product of the hydrogenation process.