A galvanic cell which makes use of the following reaction at 298K. $Cr_2O_7^{2-}+14H^++6Fe^{2+}\rightarrow 2Cr^{3+}+6Fe^{3+}+7H_2O$.Given : $E^{\large\circ}(Cr_2O_7^{2-},H^+,Cr^{3+}|Pt)=1.33V;E^{\large\circ}(Fe^{3+},Fe^{2+}|Pt)=0.77V$.The cell emf could be increased above the standard emf by

Question

$\begin{array}{1 1}\text{increasing }[Cr^{3+}]\\\text{increasing }[Fe^{3+}]\\\text{decreasing }[Cr_2O_7^{2-}]\\\text{decreasing the }pH\end{array} $