Understand the role of pepsin: Pepsin is an enzyme that is produced in the stomach and is crucial for the digestion of proteins.
Identify the substrate: Enzymes are specific to their substrates. Pepsin specifically targets proteins, breaking them down into smaller peptides.
Consider the environment: Pepsin functions optimally in the acidic environment of the stomach, which is necessary for its activation from pepsinogen.
Eliminate incorrect options: Pepsin does not digest fats, nucleic acids, or carbohydrates. These macromolecules are broken down by other enzymes such as lipases, nucleases, and amylases, respectively.
Conclude with the correct answer: Based on the specificity of pepsin for proteins, the correct answer is that pepsin enzymatically digests proteins.