We know,

Energy density $$ = {1 \over 2}{\varepsilon _0}{E^2}C$$

$$ \Rightarrow {{Energy} \over {Volume}} = {1 \over 2}{\varepsilon _0}{E^2}C$$

$$ \Rightarrow Energy = {1 \over 2}{\varepsilon _0}E_c^2x\,vol$$

Given that, $${\left( {Energy} \right)_1} = {\left( {Energy} \right)_2}$$

$$ \Rightarrow {1 \over 2}{\varepsilon _0}E_1^2cx\pi R_1^2{L_1} = {1 \over 2}{\varepsilon _0}E_2^2cx\pi R_2^2{L_2}$$

$$ \Rightarrow E_1^2R_1^2{L_1} = E_2^2R_2^2{L_1}\,(as\,{L_1} = {L_2})$$

$$ \Rightarrow E_1^2R_1^2 = E_2^2R_2^2$$

$$ \Rightarrow {E_1}{R_1} = {E_2}{R_2}$$

$$ \Rightarrow {E_1}{R_1} = {E_2}\left( {{{{R_1}} \over 2}} \right)\,\left( {As\,{R_2} = {{{R_1}} \over 2}} \right)$$

$$ \Rightarrow {E_2} = 2{E_1} = 2 \times 100$$

$$ \Rightarrow {E_2} = 200\,N/C$$

Hence, option (3) is correct.