Right option is (d) Increasing the pH to make it highly basic
Best explanation: Both aqueous and oil solutions can be used for controlled drug release. The aqueous solution the release can be controlled by increasing the viscosity of the vehicle by use of MC, CMC, PVP. BY forming complexes with macromolecules like MC, CMC, or PVP. By forming complexes that control drug release not by dissociation but by reducing the solubility of the parent drug.