Vitamins are the organic compounds required in the diet in small amounts to perform specific biological functions for normal maintenance of optimum growth and health of the organism. Vitamins are classified into two groups depending on their solubility in water or fat. Vitamins which are soluble in fat and oils but insoluble in water are fat-soluble vitamins. Fat-soluble vitamins are vitamins A, D, E and K. Fat-soluble vitamins are stored in the liver and adipose tissues. Vitamins of B group and vitamin C are soluble in water and are known as water-soluble vitamins. Water-soluble vitamins must be supplied regularly in the diet because they are readily excreted in urine and cannot be stored (except vitamin B₁₂) in our body. Plants can synthesize all vitamins whereas only a few vitamins like vitamin K, vitamin A from carotene, and some members of the vitamin B complex are synthesized in the human body. Vitamins catalyze biological reactions in very low concentrations. Multiple deficiencies caused by a lack of more than one vitamin are called avitaminosis.

Chemically digestion is

hydrolysis

Chemically, digestion is hydrolysis. Hydrolysis is a chemical reaction that breaks down a molecule by adding water. In the case of digestion, food molecules are broken down into smaller molecules by enzymes that add water. These smaller molecules can then be absorbed by the body.

Hydrogenation is a chemical reaction that adds hydrogen to a molecule. Anabolism is a chemical reaction that builds up molecules from smaller molecules. Dehydrogenation is a chemical reaction that removes hydrogen from a molecule.

Therefore, the answer is (2).