For the Cell Cu(s)|Cu²⁺||Ag⁺|Ag(s),the Standard Cell Potential Is 0

For the cell Cu(s) |Cu²⁺||Ag⁺|Ag(s) ,the standard cell potential is 0.46 V.A cell using these reagents was made,and the observed potential was 0.29 V at 25^oC.What is a possible explanation for the observed voltage?

A) The volume of the Cu²⁺ solution was larger than the volume of the Ag+ solution.
B) The volume of the Ag⁺ solution was larger than the volume of the Cu²⁺ solution.​
C) The Cu²⁺ concentration was larger than the Ag⁺ concentration.
D) The Ag electrode was twice as large as the Cu electrode.
E) The Ag⁺ concentration was larger than the Cu²⁺ concentration.