• Corrin Ring System: The core macrocyclic framework of Vitamin $\text{B}_{12}$ (Cobalamin) consists of a corrin ring containing four reduced pyrrole rings linked directly (lacking one methine bridge present in porphyrin) coordinated to a central cobalt ($Co$) ion.
• Comparative Rings: Vitamin $\text{B}_1$ (thiamine) contains thiazole and pyrimidine rings; Vitamin $\text{B}_2$ (riboflavin) contains an isoalloxazine ring; Vitamin $\text{B}_6$ contains a pyridine ring.

Correct option: (4) Vitamin By

• Statement (I) is False: Competitive enzyme inhibition is classically reversible; because the competitive inhibitor binds non-covalently to the catalytic substrate-binding pocket, it can be completely displaced by increasing substrate concentration ($[S]$).
• Statement (II) is False: In competitive inhibition, the apparent maximum velocity remains completely unchanged ($V_{\max}^{\text{app}} = V_{\max}$). It is the apparent Michaelis constant ($K_m$) that increases by the factor $\alpha$ ($K_m^{\text{app}} = \alpha K_m$).
• Conclusion: Both Statement (I) and Statement (II) are false.

Correct option: (2) Both Statement (I) and Statement (II) are false.

• Serine Protease Catalytic Triad: Chymotrypsin is a pancreatic endopeptidase belonging to the Serine Proteases superfamily.
• Catalytic Mechanism: It utilizes an invariant catalytic triad composed of Ser195, His57, and Asp102. The histidine acts as a general base to deprotonate Ser195, generating a potent alkoxide nucleophile that attacks the substrate carbonyl carbon to form a covalent acyl-enzyme intermediate.

Correct option: (2) Serine Proteases