Final answer:
Amino acids are organic compounds that serve as the building blocks of proteins, containing both an amine and carboxylic acid group. option c is correct.
Step-by-step explanation:
Amino acids are organic compounds that are the fundamental building blocks of proteins. These molecules contain an amine (-NH₂) and a carboxylic acid (-COOH) group, with a distinctive side chain or R group specific to each amino acid. An example of an amino acid is alanine. In nature, proteins are constructed from a set of 20 common amino acids, sometimes referred to as 'α-amino acids', which have the amino group attached to the α-carbon of the carboxylic acid unit.
While humans and other organisms can synthesize some of these amino acids, others must be obtained through the diet and are known as essential amino acids. These amino acids are necessary for synthesizing proteins in the body yet are not produced internally and include amino acids like Methionine, Valine, and Lysine, among others.
Beyond the standard set, additional amino acids like Selenocysteine and Pyrrolysine have been discovered in proteins, although they appear in much smaller quantities. This variety and complexity allow proteins to fulfill a vast array of biological functions.