Which of the following is a large molecule composed of amino acids?

A protein is a large molecule composed of amino acids, which are the building blocks of proteins. These amino acids are linked together in specific sequences through peptide bonds, forming polypeptide chains that fold into unique three-dimensional structures. The complex structure of proteins enables them to perform a wide variety of functions in living organisms, including catalyzing biochemical reactions as enzymes, serving as structural components in cells, and facilitating communication between cells.

In contrast, carbohydrates are organic compounds made primarily of carbon, hydrogen, and oxygen, and consist of sugar molecules, while lipids include fats and oils, which are hydrophobic molecules primarily made up of fatty acids and glycerol. Nucleic acids, such as DNA and RNA, are macromolecules composed of nucleotide units, not amino acids, and are involved in the storage and transmission of genetic information. Hence, among the provided options, a protein distinctly fits the description of a large molecule composed of amino acids.