c
As no current flows through arm $E B$ then
$\mathrm{V}_{\mathrm{D}}=0\, \mathrm{V}$
$\mathrm{V}_{\mathrm{E}}=0\, \mathrm{V}$
$\mathrm{v}_{\mathrm{B}}=-4 \,\mathrm{V}$
$\mathrm{V}_{\mathrm{A}}=5 \,\mathrm{V}$
So, potential difference between the points
$A$ and $D$
$V_{A}-V_{D}=5\, \mathrm{V}$