An immobilized enzyme being used in a continuous plug flow reactor exhibits an effectiveness factor (η) of 1.2. The value of η being greater than 1 could be apparently due to (A) substrate inhibited kinetics with external pore diffusion limitation (B) internal pore diffusion limitation (C) sigmoidal kinetics (D) unstability of the enzyme

Answer: (B) internal pore diffusion limitation
An effectiveness factor greater than 1 indicates that internal pore diffusion limitations are likely affecting the enzyme activity, as it can cause the enzyme to be more effective than would be expected from its intrinsic activity alone. External diffusion limitations typically reduce η below 1.