In which of the following situations the distance-time graph of an object is a straight line :
(A) object is at rest
(B) object is moving with uniform speed
(C) object is in non uniform motion
(D) object is having uniform acceleration

Correct option is C

The correct answer is
→ object is at rest
The change in the position of an object with time can be represented on the distance-time graph. When an object travels equal distances in equal intervals of time, then it moves with uniform speed. This shows that the distance travelled by the object is directly proportional to the time taken. Thus, for uniform speed, a graph of distance travelled against time is a straight line.
→ Object is moving with uniform speed
If u = 0 and f = 0 then also the above variation of h with t is valid (As f = 0 for u=0 which is fulfilling the conditions for the above case). Therefore, it can be concluded that the object is in uniform motion or is at rest.