Which term describes a large molecule made up of many repeating subunits?

The term that describes a large molecule made up of many repeating subunits is "polymer." Polymers are formed when many smaller units, known as monomers, chemically bond together in a process called polymerization. This structure allows polymers to exhibit unique physical and chemical properties compared to their individual monomer components. For instance, common examples of polymers include plastics like polyethylene and biological macromolecules such as proteins and nucleic acids, which are essential to life.

The other terms like monomer, trimer, and complex carbohydrate do not accurately describe this concept. A monomer refers to a single building block that can join with others to form a polymer. A trimer specifically indicates a molecule composed of three repeating units, which does not encompass the broader category of large molecules formed by numerous subunits. Lastly, while a complex carbohydrate is indeed a type of polymer (specifically made of sugar units), it is just one specific example and does not cover the entirety of what a polymer can represent. Thus, polymer is the correct and most inclusive term for a large molecule made up of many repeating subunits.