a
\(\begin{array}{l}
For\,the\,{\rm{distance}}\,{\rm{covered}}\,{\rm{in}}\,{\rm{the}}\,{\rm{last}}\,\\
{\rm{second}},\,final\,velocity\,brcomes\,zero.\\
So\,if\,we\,drop\,an\,object\,with\,zero\,\\
velocity\,it\,will\,{\rm{cover}}\,{\rm{the}}\,{\rm{same}}\,{\rm{distance}}\\
{\rm{in}}\,{\rm{one}}\,{\rm{second}}\,{\rm{while}}\,{\rm{going}}\,{\rm{downwards}}{\rm{.}}\\
{\rm{now}}\,{\rm{distance}}\,{\rm{travelled}}\,{\rm{in}}\,{\rm{the}}\,{\rm{later}}\,{\rm{case}}\\
{\rm{s}}\, = ut + \frac{1}{2}g{t^2} = 0 + \frac{1}{2} \times 10 \times 1\\
s\, = 5m
\end{array}\)