What is a polymer?

A polymer is defined as a large molecule that consists of repeated subunits, which can also be referred to as monomers. These monomers are chemically bonded in long chains, resulting in materials with unique properties and characteristics based on their structure and composition. Polymers can be natural, like proteins and DNA, or synthetic, such as plastics and nylon.

The nature of polymers allows them to exhibit a wide range of physical and chemical properties, making them versatile materials used in various applications — from everyday items to high-performance components in engineering and technology. Understanding the structure of polymers and how their monomeric units are arranged provides insight into their behavior, processing, and function in practical applications.

This choice correctly identifies the key aspect of polymers, which is their large molecular size arising from the repetition of smaller monomer units.