Which of the following amino acids possesses a nonpolar, nonaromatic side chain?

Glycine is indeed the amino acid that possesses a nonpolar, nonaromatic side chain. Its side chain consists of just a single hydrogen atom, making it the simplest amino acid. As a result, glycine does not have a charge and is classified as nonpolar. The small size of its side chain allows it to fit easily in various environments within proteins, often contributing to the flexibility of polypeptide chains.

On the other hand, tyrosine contains a polar hydroxyl (-OH) group in its side chain, which contributes to its polar character. Asparagine has a polar amide group in its side chain, making it also a polar amino acid. Cysteine, while considered less polar than some other amino acids, has a thiol (-SH) group that can participate in bonding interactions, contributing to areas of polarity within proteins. Thus, among the choices provided, glycine is the only amino acid with a truly nonpolar, nonaromatic side chain.