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: <br>

Question

( A ) $\frac{Q}{8 \pi \varepsilon_0 L}$
( B ) $\frac{Q \; In \; 2}{4 \pi \varepsilon_0 L}$
( C ) $\frac{Q}{4\; \pi\; \varepsilon_0 \;L\; In\; 2}$
( D ) $\frac{3Q}{4 \pi \varepsilon_0 L}$