A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction . Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?

• A. Inner catalyst core of radius R/8 does not participate in reaction.
• B. Inner catalyst core of radius R/2 does not participate in reaction.
• C. Inner catalyst core of radius 7R/8 does not participate in reaction.
• D. Effectiveness factor for a zero order reaction can not be 7/8 as it must always be 1.