What is a naturally occurring or synthetic compound made of large molecules linked by simple monomers?

The correct answer is a polymer. Polymers are large, complex molecules composed of repeated subunits known as monomers. These monomers can be natural, such as sugars in polysaccharides, or synthetic, like plastic materials derived from petrochemicals. The process through which monomers link together to form polymers is called polymerization.

Understanding this concept is crucial because it establishes the foundation for many biological and chemical processes. For instance, proteins are polymers formed from amino acid monomers, and they play vital roles in the structure and function of living organisms. Recognizing polymers and their formation will help in studying macromolecules and their implications in various scientific fields, including genetics, materials science, and biochemistry.

The other terms mentioned do not accurately describe the large molecule structure described in the question. Monomers refer to the individual units that make up polymers, alleles are variations of a gene found at the same locus on chromosomes, and X-ray diffraction is a technique used to study the structure of molecules, not a type of compound.