A particle has speed $6.25 m/s$ is decelerated at sale of given by $\large\frac{dv}{dt}$$=-2.5 \sqrt {v}$ where v is instantaneous speed. The time taken for the object to come to real is

Question

$\begin{array}{1 1} (a) \;6\;sec \\ (b) \;2\;sec\\ (c) \;10\;sec \\ (d) \;12\;sec\end{array} $