a
(a) The distance covered by the ball during the last \(t\) seconds of its upward motion = Distance covered by it in first \(t\) seconds of its downward motion
From\(h = ut + \frac{1}{2}g\,{t^2}\)
\(h = \frac{1}{2}g\;{t^2}\) [As \(u = 0\) for it downward motion]