The correct answer is A. Fats, proteins, and carbohydrates.

The pancreas secretes digestive enzymes into the small intestine to break down:

- Fats: pancreatic lipase - Break down triglycerides into fatty acids and glycerol

- Proteins: pancreatic amylase, trypsin, and chymotrypsin -  Break down proteins into amino acids

- Carbohydrates: pancreatic amylase - Break down carbohydrates into simple sugars

The other options are not correct:

B. Vitamins are not broken down by pancreatic enzymes, and cellulose is broken down by microbial enzymes in the large intestine.

C. Vitamins are not broken down by pancreatic enzymes.