For uniform motion :
(a) the distance-graph is a straight line parallel to the time axis.
(b) the speed-time graph is a straight line inclined to the time axis.
(c) the speed-time graph is a straight line parallel to the time axis.
(d) the acceleration-time graph is a straight line parallel to the time axis.
The solution is C.
The speed-time graph is a straight line parallel to the time axis. This means that the speed is constant, i.e., the body travels equal distances in equal intervals of time.