A particle is projected with a certain velocity at an angle \[\alpha \] above the horizontal from the foot of an inclined plane of inclination\[30{}^\circ \]. If the particle strikes the plane normally, then \[\alpha \] is equal to

• A. \[30{}^\circ +\,te{{n}^{-1}}(\frac{\sqrt{3}}{2})\]
• B. \[45{}^\circ \]
• C. \[60{}^\circ \]             
• D. \[30{}^\circ \,+\,te{{n}^{-1}}(2\sqrt{3})\]