Can a body have
a. Zero instantaneous velocity and yet be accelerating?
b. Zero average speed but non-zero average velocity?
c. Negative acceleration and yet be speeding up?
d. Magnitude of average velocity be equal to average speed ?

Explanation

a. Yes for example, a freely falling particle at its highest point has zero velocity but acceclerating downward.
b. No , if distance is zero then displacement is also zero,
c. Yes if velocity is also in the negative direction.
d. Yes if motion takes place continuously in one dirction.