Final answer:
Metals are not macromolecules, as they do not form polymeric structures like proteins, carbohydrates, nucleic acids, and lipids do.
Step-by-step explanation:
The choice that is not a macromolecule is c. Metals. Macromolecules are large, complex molecules that are crucial for life and include proteins, carbohydrates, nucleic acids, and lipids. These macromolecules are composed of smaller units known as monomers which are joined by covalent bonds, forming larger polymers through a process known as dehydration synthesis, where a water molecule is released as two monomers are joined together. Metals, on the other hand, do not form such polymeric structures and are considered simple elements or minerals but not organic compounds or macromolecules.