Final answer:
The daily motion of objects in the sky is primarily caused by the rotation of Earth on its axis, leading to the regular alternation of day and night .Option 4 is the correct answer.
Step-by-step explanation:
The daily motion of objects in the sky is primarily caused by the rotation of Earth on its axis. This rotational motion happens every 24 hours and is responsible for alternately exposing different parts of the planet to the sun, thus causing day and night.
While factors like the precession of Earth's axis and the revolution of Earth around the Sun play roles in the long-term movement of celestial bodies and the progression of the seasons.
Earth's rotation that gives rise to the apparent daily movement of the stars, sun, and moon across the sky.