During the electrolysis of carnallite, MgCl2 is decomposed and not KCl. This is because of :
a. lower decomposition voltage of MgCl2 than that of KCl
b. reverse reaction MgCl2+2K⟶Mg+2KCl if KCl is decomposed under other experimental condition
c. both (a) and (b)
d. none of the above