**Core Concept**
Trypsin is a serine protease enzyme that plays a crucial role in protein digestion in the gastrointestinal tract. It is a key component of the digestive process, responsible for breaking down proteins into smaller peptides and amino acids.

**Why the Correct Answer is Right**
Trypsin specifically cleaves the peptide bonds at the carboxyl side of the amino acids lysine (K) and arginine (R), except when either of these amino acids is followed by proline. This specificity is due to the unique active site of the trypsin enzyme, which recognizes and binds to the positively charged side chains of lysine and arginine. The enzyme then hydrolyzes the peptide bond between these amino acids, releasing smaller peptides into the digestive system.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because trypsin does not specifically cleave the peptide bonds at the carboxyl side of the amino acid glutamine (Q). Glutamine is a neutral amino acid and is not recognized by the trypsin enzyme.
**Option B:** This option is incorrect because trypsin does not specifically cleave the peptide bonds at the carboxyl side of the amino acid tyrosine (Y). Tyrosine is a hydrophobic amino acid and is not recognized by the trypsin enzyme.
**Option C:** This option is incorrect because trypsin does not specifically cleave the peptide bonds at the carboxyl side of the amino acid glycine (G). Glycine is a small, neutral amino acid and is not recognized by the trypsin enzyme.

**Clinical Pearl / High-Yield Fact**
Trypsin is an important enzyme in the digestive process, and its activity is regulated by several mechanisms, including feedback inhibition by peptides and amino acids. This regulation helps maintain a balanced digestive process and prevents excessive protein degradation.

**Correct Answer: D. Lysine and Arginine**