Explanation:

When a body starts from point A and reaches point B in a straight line, and then returns back to point A, it covers a total distance of twice the distance between point A and point B. However, the displacement of the body is zero as the body ends up at the same point from where it started.

Distance and Displacement:

Distance refers to the total path covered by the body, while displacement refers to the change in position of the body. In this scenario, the distance covered by the body is twice the distance between point A and point B, while the displacement is zero.

Velocity:

The velocity of the body is the rate of change of displacement over time. Since the displacement of the body is zero in this scenario, the velocity of the body is also zero.

Acceleration:

Acceleration is the rate of change of velocity over time. If the body moves with a constant velocity, there is no acceleration. However, if the body changes its velocity, there is acceleration. In this scenario, when the body turns around at point B, its velocity changes, and hence there is acceleration.

Conclusion:

In summary, when a body starts at point A, reaches point B in a straight line, and then returns back to point A, it covers a total distance of twice the distance between points A and B, but its displacement is zero. The velocity of the body is zero, but there is acceleration when the body turns around at point B.

Ans is Displacement..... because the boy starting with "A" and return back to "A" ........and displacement is the shortest path covered by an object therefore displacement will be zero....