Step 1: Recall each process.
- Caramelization: Heat-induced browning of sugars → related to sugar.
- Denaturation: Structural change of proteins/enzymes due to heat or pH → related to enzyme.
- Oxidation: Common in oils/fats leading to rancidity → related to lipid.
- Bleaching: Removal of natural coloring substances → related to pigment.
Step 2: Match accordingly.
- P (Caramelization) → 2 (Sugar)
- Q (Denaturation) → 4 (Enzyme)
- R (Oxidation) → 1 (Lipid)
- S (Bleaching) → 3 (Pigment)
Step 3: Verify with options.
This matches with option (A).
Final Answer:
\[
\boxed{\text{(A) P-2, Q-4, R-1, S-3}}
\]