Two balls A and B are thrown with speeds \[u\] and u/2, respectively. Both the balls cover the same horizontal distance before returning to the plane of projection. If the angle of projection of ball B is \[15{}^\circ \] with the horizontal, then the angle of projection of A is

• A. \[{{\sin }^{-1}}\left( \frac{1}{8} \right)\]
• B. \[\frac{1}{2}{{\sin }^{-1}}\left( \frac{1}{8} \right)\]
• C. \[\frac{1}{3}{{\sin }^{-1}}\left( \frac{1}{8} \right)\]
• D. \[\frac{1}{4}{{\sin }^{-1}}\left( \frac{1}{8} \right)\]