A body is thrown vertically upwards. Which one of the following graphs correctly represents the velocity vs time?

Velocity of a body thrown vertically upwards can be given as:
vf=vi+at
where a=−g (always acts in downward direction)
∴vf=vi−gt
for t<vi/g, vf is positive
at t=vi/g, we get vf=0
for t>vi/g, vf is negative.
also the slope of v vs t graph is −g [Negative]
From the above explanations, we can conclude that the velocity starts from a positive value, starts decreasing, reaches zero and keeps on decreasing to be a negative value.
Hence, the correct option is (D)