A particle is projected vertically upwards with a velocity $u$ from a point O. When it returns to the point of projection:

The correct options are
A Its average velocity is zero
B Its displacement is zero
C Its average speed is $\frac{u}{2}$
When it returns to the same point, its net displacement is zero.
Time of flight $T=\frac{2u}{g},$
Maximum height reached is $\frac{u^2}{2g}$ and total distance travelled is $\frac{u^2}{g}$
Average velocity $=\frac{\text{displacement}}{\text{time}}=0$
Average speed $=\frac{\text{distance}}{\text{time}}=\frac{\frac{u^2}{g}}{\frac{2u}{g}}=\frac{u}{2}$