# Refer to the below equation :

$\begin{array}{1 1}(a)\;0.166V&(b)\;0.53V\\(c)\;-0.53V&(d)\;-0.166V\end{array}$

By Flesr law
$\Delta G_3=\Delta G_1+\Delta G_2$
$-3\times F\times E ^o=-1\times F\times 0.77+2\times F\times 0.41$
$3E^o=0.77-0.82$
$E^o=-0.166V$
Hence (d) is the correct answer.