
option $A$ is incorrect.
The two sphere system act as the concentric sphere capacitor.
By Gauss'law, The electric field is zero inside $A$ and outside the $B$.
But it is $non-zero$ between $A$ and $B$.
So option $\mathrm{B}$ and $\mathrm{D}$ are incorrect.
option $C$ is incorrect.


$\left\{ Use : \frac{1}{4 \pi \varepsilon_{0}}=9 \times 10^{9} Nm ^{2} C ^{-2}\right\}$
