The dipole moment of a hydrogen halide $H-X$ is 1.80 and the bond length is 1.5$A^{\large\circ}$.The percentage of ionic character of H-X bond will be :$(e=4.8\times 10^{-10}$e.s.u)

Question

$\begin{array}{1 1}(a)\;40\%&(b)\; 80\%\\(c)\;25\%&(d)\;60\%\end{array}$