Correct Answer - A::C
If an object undergoes a displacement `Delta r` in time `Delta t`, its average velocity is given by
`v=(Deltar)/(Delta t)=(r_(2)-r_(1))/(t_(2)-t_(1))`, where `r_(1)` and `r_(2)` are position vectors corresponding to time `t_(1)` and `t_(2)`.
It the velocity of an object changes from `v_(1)` to `v_(2)` in time `Delta t`. Average acceleration is given by
`a_(av)=(Deltav)/(Delta t)=(v_(2)-v_(1))/(t_(2)-t_(2))`
But , when acceleration is non-uniform
`v_("av")!= (v_(1)+v_(2))/(2)`
We can write `" " Delta v=(Delta r)/(Delta t)`
Hence, `" " Delta r=r_(2)-r_(1)=(v_(2)-v_(1))(t_(2)-t_(1))`