Final answer:
To process Fe and N from food, digestive enzymes are required. These enzymes facilitate the chemical digestion needed to break down complex food molecules into absorbable units like amino acids.
Step-by-step explanation:
The process required to extract and utilize iron (Fe) and nitrogen (N) from food involves digestive enzymes. These enzymes break down food during chemical digestion, a process essential for transforming complex macromolecules such as proteins and fats into absorbable units like amino acids and fatty acids. Dietary iron is absorbed in the duodenum and requires an acidic environment for optimal absorption, whereas nitrogen is primarily obtained through the consumption of proteins and is processed in the form of amino acids. Digestive enzymes are responsible for this breakdown and thus the correct answer to the question is D) Digestive enzymes.