b
\(R=\frac{\rho \ell}{A}=\frac{\rho \ell}{(V / \ell)}=\frac{\rho \ell^{2}}{V} \quad(V \rightarrow \text { Volume of wire })\)

\(\Rightarrow\) Final resistance \(=3 \times(\mathrm{B})^{2}=12\, \Omega\)

\(\begin{aligned} \mathrm{R}_{\mathrm{eq}} &=2 \,\Omega \| 10\, \Omega \\ &=\frac{5}{3}\, \Omega \end{aligned}\)