Hint:Nucleotides are defined as building blocks of nucleic materials DNA and RNA. These nucleotides are found in living cells and are known to contain the genetic information of an organism. They have four bases including- Adenine, Thymine, Guanine, and Cytosine. These form base pairing in nucleic material.
The full form of NAD is Nicotinamide Adenine Dinucleotide. It is defined as a cofactor in the metabolism process. It is found in all the living cells and it is named so because it contains two nucleotides attached with their phosphate groups. One among the two has an adenine nucleobase and the other is nicotinamide.
NAD is known to exist in two forms in cells as an oxidized form which is abbreviated as NAD+ and a reduced form which is abbreviated as NADH, Here H stands for hydrogen.
The main function of NAD is known to be the function of electron transfer or in metabolism, it is seen to carry out most of the redox reactions carrying the electrons from one reaction to the other.
In living organisms, NAD is believed to be synthesized from the simple building blocks including amino acids either tryptophan or aspartic acid. More complex forms are synthesized from niacin. Some of the NAD is converted to a coenzyme which is Nicotinamide Adenine Dinucleotide Phosphate (NADP) which mainly acts as the cofactor for many anabolic reactions.
NAD is involved in many of the reactions of the body, most important being acting as a coenzyme required for catalysis of many biochemical reactions by different enzymes involving the transfer of electrons.
So, the correct answer to this question is the option"C".
Note: As we know NAD is required for metabolism in living cells and therefore one having a deficiency of NAD should take a healthy diet, protect the body from a lot of sunlight, and should take supplements which are having NAD. NAD is important for many metabolic processes of the body.