Step 1: Understanding Disulphide Bridges
- Disulphide bonds (\( S-S \) bonds) form between cysteine residues in proteins, providing stability.
- These bonds are important for tertiary and quaternary structures, preventing unfolding.
Step 2: Evaluating the Assertion and Reason
- (A) is correct: Disulphide bonds contribute to protein stability.
- (R) is correct: Sulphur indeed forms disulphide bonds, and these are crucial in higher-order structures.
- (R) correctly explains (A), making option (A) correct.