Correct option is (c) Glass pH electrode
Best explanation: Glass pH electrode consists of gas permeable membrane selective for CO2, NH3 or H2S. The diffusion of the gas through this membrane causes a change in pH of a sensing solution between the membrane and the electrode which is then determined. Glass electrode has a hydrated glass membrane which generates transverse electric potential. Solid-state electrodes has thin membrane of a specific ion conductor made from a mixture of silver sulphide and a silver halide. Clark oxygen electrode is used in amperometric biosensor.