Coenzyme is often a
Enzymes are proteins which help to catalyze the biochemical reaction. The enzyme has a protein part which is not active is known as apoenzyme. It gets activated by the addition of an organic or inorganic cofactor. The holoenzyme is defined as apoenzyme in combination with the cofactor. A cofactor is a non-protein part of the enzyme. It can be metal ions or the organic chemical. The cofactors which are organic chemicals are known as a coenzyme. Vitamins serve as a coenzyme. Vitamin B serves as a coenzyme for the formation of fat and carbohydrate. So, the correct answer is option D.