Protein breaks down into

Mostly into carbohydrates and fats.

Explanation:

"They mostly break down carbohydrates and fats. Once a protein source reaches your stomach, hydrochloric acid and enzymes called proteases break it down into smaller chains of amino acids. Amino acids are joined together by peptides, which are broken by proteases" - Protein Digestion: Enzymes, Absorption, and Ways to Improve

"Dietary protein is a vital source of amino acids. Proteins ingested in the diet are digested into amino acids or small peptides that can be absorbed by the intestine and transported in the blood." - Proteins Are Degraded to Amino Acids - Biochemistry - NCBI

I made sure to give credit to the sources. Hopefully this helps!!!

chordata is the answer

the answer is d p: cell, q: organ, r: organ system, s: tissue