(N/A) $(i)$ The velocity-time graph is a straight line passing through the origin,indicating that velocity increases linearly with time. Therefore,it represents uniformly accelerated motion.
$(ii)$ The velocity-time graph is a straight line parallel to the time axis,indicating that velocity remains constant over time. It represents uniform motion (zero acceleration).
$(iii)$ The velocity-time graph is a straight line with a negative slope,indicating that velocity decreases linearly with time. It represents uniformly retarded motion (uniform deceleration).
$(iv)$ The velocity-time graph is a curve with a negative slope,indicating that the rate of decrease of velocity is not constant. It represents non-uniformly retarded motion.