Answer: The correct answer for the blank is- b. proteins.
Proteins are one of the four major macromolecules that are essential for the life forms ( as they are involved in most of the metabolic reactions). They are formed by long chains of small molecules that are called amino acids ( also referred as building blocks of proteins).
Amino acids are joined to each other using peptide bond in a process called translation. There are primarily 20 amino acids that make up proteins ( out of them 10 are essential that can not be synthesized by body and are obtained from external food source).
