A stone is projected at a certain angle. Two seconds before it reaches the maximum height it makes $60^{\circ}$with the horizontal.what is the velocity of the stone at highest point

Question

$\begin{array}{1 1} 15\;m/s \\ \large\frac{20}{\sqrt 3} \normalsize m/s \\ 20\sqrt3 m/s \\ 10 m/s \end{array}$