________ are natural or synthetic materials made up of long molecular chains of identical chemical subunits.

• A. Polymers
• B. Ceramics
• C. Metals
• D. Composite

Answer: (A)

Polymers are large molecules built from many repeating units called monomers joined into long chains. This chain-like structure can occur in natural materials (like cellulose, DNA, proteins, starch) or be created synthetically (such as polyethylene, nylon, PVC). The long, identical subunit chains give polymers distinct properties—flexibility, toughness, and the ability to form films and fibers. Ceramics are brittle inorganic solids without long chain molecular structure; metals are bonded in a lattice of atoms rather than chains of repeating subunits; composites combine two or more materials and aren’t defined by long polymer chains themselves. So the description fits polymers.