Option B is correct because both statements are factually true according to the provided text, but the reason does not explain the assertion. The text states that structurally, insulin consists of two chains, A and B, 'interconnected with disulphide bonds' (supporting the Assertion). It also states that in the process of forming active insulin, the 'C-chain... are removed' (supporting the Reason). However, the removal of the C peptide is a processing step to activate the insulin; it does not explain the chemical presence or formation of the disulfide bridges that link the A and B chains. The text mentions that disulfide bonds were 'reestablished' to reconstruct the insulin, indicating they are structural elements distinct from the C peptide removal process.