A charge Q is uniformly distributed over a long rod AB of length L as shown in the figure. The electric potential at the point O lying at a distance L from the end A is :

Question

$\begin{array}{1 1} (1) \large\frac{Q}{8 \pi \in_0 L} \\ (2)\large\frac{3Q}{4 \pi \in_0 L} \\ (3)\large\frac{Q}{4 \pi \in_0 L ln_2} \\ (4) \large\frac{Qln2}{4 \pi \in_0 L}\end {array}$