Answer:
t=1.43 s
Option A is the correct option.
Solution,
S=10 m
u=0 m/s
a=9.8 m/s^2
Now,
[tex]2s = a {t}^{2}  \\ or \:  {t}^{2}  =  \frac{2 \times 10}{9.8}  \\ or \:  {t}^{2}  =  \frac{20}{9.8}  \\ or \:  {t}^{2}  = 2.04 \\ or \: t =  \sqrt{2.04}  \\ t = 1.43 \: seconds[/tex]
hope this helps...
Good luck on your assignment...