The velocity-time graph shown in the question represents the motion of an object over time. Option 1 states that the graph represents uniform acceleration, but this is not correct. Uniform acceleration would be indicated by a straight line on the graph, whereas this graph shows a curve that is decreasing over time.

Option 2 states that the graph represents uniform retardation of an object, which is the correct answer. Retardation refers to the object slowing down or decelerating, which is evident from the decreasing velocity shown on the graph. The curve indicates a constant rate of decrease in velocity, indicating uniform retardation.

Option 3 suggests non-uniform acceleration of an object, but this is not the case. Non-uniform acceleration would result in a non-linear graph, with varying rates of change in velocity.

Option 4 suggests non-uniform retardation of an object, but this is also not correct. The graph shows a consistent decrease in velocity, indicating uniform retardation.

Therefore, the correct answer is option 2, which accurately describes the motion portrayed by the velocity-time graph as uniform retardation.