What is the process of digestion mainly responsible for?

The process of digestion is primarily responsible for breaking down large food particles into smaller molecules. This breakdown occurs through mechanical processes, such as chewing and mixing with saliva, as well as chemical processes, like the action of digestive enzymes that further decompose food into simpler forms. This reduction in size and complexity is essential because it allows the smaller molecules, such as amino acids, fatty acids, and simple sugars, to be efficiently absorbed into the bloodstream during the absorption phase that follows digestion.

The importance of this process cannot be overstated, as only properly broken-down nutrients can be transported across the intestinal lining and into the bloodstream, where they can then be utilized by the body for energy, growth, and repair. Understanding that the primary role of digestion is this mechanical and chemical breakdown clarifies its foundational role in nutrition and metabolism, making option B the correct choice.