Right answer is (d) Effectiveness factor
To explain I would say: The above graph shows the effect of particle diameter on the effectiveness factor of immobilized enzymes. Effectiveness factor is given by \(ƞ=\frac{V}{V_{free}}\), where
V = rate of reaction catalyzed by immobilized enzymes
Vfree = rate of reaction catalyzed by free enzymes
The red dotted line and blue non-dotted line represents the effect of particle diameter on the effectiveness factor at high surface concentration of the enzyme and at small surface concentration of the enzyme. According to the graph, as particle diameter decreases the effectiveness factor also decreases for high surface concentration and for small surface concentration, initially it is maintained and then decreases gradually. The ‘X’ in the plot represents effectiveness factor.