c
\(\begin{array}{l}
{Y_{cm}}from\,ground\, = \frac{{0.03 \times 100}}{{0.05}} = 60\,m\\
{V_{cm}} = \frac{{0.02 \times 100}}{{0.05}} = 40\,m/s\\
H = \frac{{V_{cm}^2}}{{2g}} = \frac{{40 \times 40}}{{20}} = 80\,m
\end{array}\)
Height above building \(= 80 - 40 = 40\, m\)
