Question

If the position- time graph is a straight line parallel to the time ​

Answer 1

When the slope of distance-time graph is a straight line parallel to time axis, the object is at the same position as the time passes. That means the object is at rest.

Answer 2

speedspeed time graph is a straight line parallel to the time axis. it means that the speed of the object is not changing with time. I.e. the object is performing uniform motion