Option (c) is correct.
Explanation:
initial velocity along vertical=0
velocity along horizontal Vx
acceleration along the vertical=9.8 m/s²
displacement along vertical,h=40 m
distance along horizontal= 10 m
using the kinematic equation
h= vi*t + 1/2 g t²
40=0(t) + 1/2 (9.8)t²
t²=8.163
t=2.857 s
now the displacement along vertical= x= Vx* t
10=Vx (2.857)
Vx=3.5 m/s
