The correct choice is (b) Dependence of the activity of immobilized enzymes in biphasic systems
The best I can explain: The plot represents schematic diagram showing the dependence of the activity of immobilised enzymes in biphasic systems. It shows a clear correlation between the activity of biocatalysts in two-phase systems and the Log P as a S-shaped curve. This plot suggests that enzymes are generally inactivated by solvents with log P < 2, but are little affected by solvents with Log P > 4. There is some variation in the effects between different enzymes and different solvents which makes activity prediction rather imprecise between 2 – 4 of log P. The range 2 – 4 includes some of the most utilized organic phases which may be suitable for some and harmful in others. The solubility of the reactants and products may considerably reduce the range of log P that are available for a particular application because many basically nonpolar molecules possessing some polar structural regions cause lack of solubility in strongly hydrophobic solvents.