What process involves the addition of water molecules to break down covalent bonds within macromolecules?

The process that involves the addition of water molecules to break down covalent bonds within macromolecules is hydrolysis. During hydrolysis, water is used to cleave the bonds that hold the monomers together in larger molecules such as proteins, carbohydrates, and lipids. This reaction is essential for digestion, where complex food substances are broken down into smaller, absorbable components.

The term "hydrolysis" literally means "water splitting," which accurately describes the function of this process in facilitating the breakdown of macromolecules. In contrast, condensation refers to the process of forming larger molecules through the removal of water, while combustion involves the reaction of a substance with oxygen, and fermentation is a metabolic process used by microorganisms to convert sugars into acids, gases, or alcohol in the absence of oxygen. Thus, hydrolysis is the correct choice because it specifically describes the mechanism of breaking down macromolecules through the incorporation of water.