a b c d

b

$\text{Electric Field } \vec{E} = -\frac{dV}{dr} = \frac{k}{r^2} \hat{r}$ $ \vec{E} =  \frac{k}{r^3} \vec{r}$ $|\vec{r}| = 7 $ $\Rightarrow \vec{E} =  \frac{k}{343} (2\hat{i} + 3\hat{j} + 6\hat{k})$