$A$ solid sphere of radius $r_1=1 \text{ cm}$ carries charge distributed uniformly over it with density $\rho_1=-3 \text{ C/cm}^3$. It is surrounded by a concentric spherical shell of radius $r_2=2 \text{ cm}$ carrying uniform charge density $\rho_2=0.5 \text{ C/cm}^3$. If $E_d$ denotes the magnitude of the electric field at distance $d$ from the common centre of the spheres,then

• A
  $E_d=\frac{1}{3 \varepsilon_0 d^2}, d \leq 1 \text{ cm}$
• B
  $E_d=\frac{1}{\varepsilon_0 d^2}, d \leq 1 \text{ cm}$
• C
  $E_d=\frac{d}{3 \varepsilon_0}, d \leq 1 \text{ cm}$
• D
  $E_d=\frac{d}{\varepsilon_0}, d \leq 1 \text{ cm}$