Two neutral conducting spheres of diameters \(8 \mathrm{~cm}\) and \(2 \mathrm{~cm}\) separated with a distance of \(15 \mathrm{~cm}\) between their centres are joined by a thin conducting wire. A charge of \(100 \mathrm{nC}\) is given to one of the spheres and the system is allowed to reach electrostatic equilibrium. The electric potential at a point on the line joining the centres of the two spheres where the net electric field becomes zero is ____ V. (Neglect the charge acquired by the wire and \(\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9 \mathrm{Nm}^2 \mathrm{C}^{-2}\))

1. A \(10.8 \times 10^3\)
2. B \(10.8 \times 10^4\)
3. C \(5.4 \times 10^3\)
4. D \(5.4 \times 10^4\)