Explanation:

Zero-gravity is the absence of gravity; a condition in which the effects of gravity are not felt; weightlessness. Microgravity is a condition of very low gravity, especially approaching weightlessness. On a spaceship, while in zero- or microgravity, objects would fall freely and float weightlessly.

• The absence of gravity is a correct and suitable reason for the weightlessness of the spaceship. If there is no downward force acting on a spaceship it means it will float in space. This flotation will feel like the experience of the weightlessness of a spaceship. Hence option 3rd is correct.