A class of compounds that are used as fragrances . . . . . . . . A. amino acid B. aromatic mixture C. ester D. bio-acid

The correct answer is C. ester.

An ester is a chemical compound formed when an acid reacts with an alcohol. Esters are often used in perfumes and other fragrances because they have a pleasant smell. Some common esters include ethyl acetate, which is found in banana oil, and amyl acetate, which is found in pear oil.

Amino acids are the building blocks of proteins. They are not used as fragrances.

Aromatic mixtures are mixtures of organic compounds that have a characteristic odor. They are not used as fragrances.

Bio-acids are acids that are produced by living organisms. They are not used as fragrances.