A voltaic cell is constructed with the overall reaction :
`Sn^(2+)(aq) + 2Ag^(+)(aq) rightarrow Sn^(4+)(aq) + 2Ag(s)`.
Which change will increase the voltage of the cell?
A. increasing `[Sn^(2+)]`
B. Increasing `[Sn^(4+)]`
C. Decreasing `[Ag^(+)]`
D. Reducing the size of the Ag electrode
