The shaded area of a velocity-time graph represents the distance covered by the particle. In velocity-time graph, the x-axis represents time and the y-axis represents velocity. The area under the graph between two time points represents the distance traveled during that time interval.

Option 1: Momentum is not represented by the shaded area of the velocity-time graph. Momentum of a particle is calculated by multiplying its mass and velocity, which is not directly related to the area under the graph.

Option 2: Acceleration is also not represented by the shaded area of the velocity-time graph. Acceleration is the rate of change of velocity with respect to time and is not directly related to the area under the graph.

Option 3: The correct answer. The shaded area represents the distance covered by the particle. It gives an indication of the total distance traveled by the particle over a certain time period.

Option 4: Speed, which is the magnitude of velocity, is not directly represented by the shaded area of the velocity-time graph. The graph shows the changes in velocity, but not the magnitude of velocity itself.