For a first order isothermal chemical reaction in a porous catalyst, the effectiveness factor is 0.3. The effectiveness factor will increase if the

• A. catalyst size is reduced or the catalyst diffusivity is reduced.
• B. catalyst size is reduced or the catalyst diffusivity is increased.
• C. catalyst size is increased or the catalyst diffusivity is reduced.
• D. catalyst size is increased or the catalyst diffusivity is increased.