Which statement best defines a monomer?

• A. A large molecule made of many repeating units
• B. A molecule used to store genetic information
• C. A small molecule that can join with others to form polymers
• D. A type of lipid that provides insulation

Answer: (C)

A monomer is a small molecule that can join with others to form polymers. This building-block idea is why this choice fits best: monomers are the basic units that link together, through bonds, to create larger, repeating structures called polymers. For example, amino acids are monomers that connect to form proteins, nucleotides form nucleic acids like DNA, and simple sugars join to make polysaccharides such as starch. The other statements describe polymers or specific functions, not the role of a monomer as a small building block that chains together to build larger molecules.