In a electrical field, the particles of a colloidal system move towards cathode. The coagulation of the same sol is studied using `K_2SO_4(I)`,Na_3PO_4(II)`,(K_4[Fe(CN)_6]`(III) and NaCI (IV). Their coagualating power should be :
A. `(I)gt(II)gt(III)gt(IV)`
B. `(III)gt(II)gt(I)gt(IV)`
C. `(III)gt(I)gt(II)gt(IV)`
D. `(IV)gt(III)gt(I)gt(II)`