What can you say about the nature of motion of a body if its displacement-time graph is
(a) a straight line parallel to time axis?
(b) a straight line inclined to the time axis with an acute angle?
(c) a straight line inclined to the time axis with an obtuse angle?
(d) a curve?
(a) The body is at rest.
(b) The body is in uniform motion and has a positive velocity.
(c) The body is in uniform motion and has a negative velocity.
(d) The body is in non-uniform motion.