All of the Following Are True for Ion-Selective Electrodes Specific

All of the following are true for ion-selective electrodes specific to aqueous ions,except:
I two reference electrodes measure the voltage difference across the ion-selective electrodes organic polymer membrane.
II the organic polymer membrane separates the inner solution from the outer analyte solution.
III the organic polymer membrane is hydrophobic and is impregnated with a viscous organic solution containing an ion exchanger and sometimes a ligand specific for the analyte ion.
IV the potential difference across the organic polymer membrane occurs when the analyte ions embedded in the membrane diffuse into the inner aqueous solution creating a junction potential.
V the potential difference is dependent only on the activity of analyte ion in the outer solution.

A) IV
B) I and V
C) I and IV
D) IV and V
E) V