Correct option is (c) stability of the enzyme
To explain: One major factor that must be addressed for the use of biphasic systems in many enzyme-catalyzed reactions is stability of the enzyme. There should be a distinction made between the more hydrophilic enzymes and the more hydrophobic enzymes which is often associated with lipid and membranes. The stability of hydrophilic enzymes depends on the presence of a thin layer of water within the microenvironment. This amount of water is minimal and can be said that the enzyme is operating in an almost anhydrous state effectively. Hydrophobic lipases retain its activity even if fewer molecules of water are remaining, assuming that it is just sufficient to stabilize the conformation of the active site.