Considering outer spherical shell is nonconducting

Electric field inside a metal sphere is zero.

\({r}<{R} \Rightarrow {E}=0\)

\({r}>{R} \Rightarrow {E}=\frac{{kQ}}{{r}^{2}}\)

Option \((1)\)

Considering outer spherical shell is conducting

\({r}<{R},{E}=0\)

\({R} \leq {r}<{a} \quad\quad {E}=\frac{{kQ}}{{r}^{2}}\)

\({a} \leq {r}<{b},\quad\quad {E}=0\)

\({r} \geq {b} \quad\quad\quad\quad\quad {E}=\frac{{kQ}}{{r}^{2}}\)