b
When the two spheres are connected by a wire, then both of them acquire the same potential say \(V\).

We also know that the electric field on the surface of a sphere \(E=\frac{Q}{4 \pi \epsilon_0 r^2}\) and potential on the surface is given by \(V =\frac{ Q }{4 \pi \varepsilon_0 T }\)

\(\Rightarrow E =\frac{ V }{ r }\)

Here, \(V\) is constant, hence \(E \propto \frac{1}{r}\)

\(\Rightarrow \frac{E_2}{E_b}=\frac{b}{a}\)