The right answer is a. they contain many small, repeating subunits bonded together.
In chemistry and biology, a polymer is a molecule made up of a chain of similar molecules, called monomers; a polymer is a macromolecule resulting from the assembly of many identical units (monomers), a chemical compound with repetitive structural units.
If the type of food available changes, then the types of bird's beaks will change with it, because their bodies are adapting to suit their environmental needs more efficiently.
