Uniform Versus Non-uniform Motion

Based on NCERT Class 11, Chapter 3 (Motion in a Straight Line), uniform motion is defined as motion in which an object covers equal displacements in equal intervals of time, however small the intervals chosen. This implies constant velocity and therefore zero acceleration. The correct option captures exactly this definition. The option about equal distances in unequal time intervals describes non-uniform motion, since changing time for the same distance means changing speed. The option about acceleration steadily increasing contradicts uniform motion, which requires zero acceleration. The option about velocity changing direction periodically describes oscillatory or circular motion, not uniform straight-line motion. Plausibility check: under uniform motion the velocity-time graph is a horizontal line and the position-time graph is a straight inclined line of constant slope; only equal displacements in equal times produce such graphs, confirming the chosen definition is the physically correct one.