Natural vs. synthetic polymers sharing amide linkages

Steps:

• Examine linkages: fats contain ester bonds from glycerol and fatty acids; proteins contain peptide bonds (amides) from amino acids; nylon contains amide bonds from polymerization.
• Identify natural occurrence: fats and proteins are natural biological molecules; nylon is a synthetic polymer.
• Match criteria: P must be natural with a specific linkage; Q synthetic with the same linkage.
• Select pair: only protein (natural amide) and nylon (synthetic amide) fit both sharing amide linkage and P natural/Q not.

Why D is correct:

• Protein (P) is a natural polymer with amide (peptide) linkages; nylon (Q) is synthetic with identical amide linkages, matching the description.

Why the others are wrong:

• A: Fat (ester linkage) and nylon (amide) have different linkages.
• B: Fat (ester) and protein (amide) have different linkages.
• C: Nylon (amide, synthetic) as P violates natural occurrence; protein as Q is natural.

Final answer: D