A ring of radius R is having charges $\; q \;and \; 3 q\;$ distributed on its two half parts . The electric potential at a point on the axis $\;\sqrt{3}\;R\;$ from its centre is

Question

$(a)\;\large\frac{3\;k\;q}{R}\qquad(b)\;\large\frac{2\;k\;q}{R}\qquad(c)\;\large\frac{k\;q}{R}\qquad(d)\;None$