Answer:
A. The movement of the Earth along its orbit
Explanation:
The moon orbits the Earth once every 27.3 days. This is the sidereal month. It is measured against the background stars.
However, the Earth is also orbiting the Sun, and the moon needs extra time to catch up to its previous position relative to the Sun. This is the synodic month. It takes 29.5 days.
B is wrong. The rotational speed of the Earth constant. It makes one revolution every 23 h 56 min 4.09053 s.
C is wrong. The synchronous rotation of the moon does not affect its orbital speed.
D is wrong. The tilt of the Earth's axis affects only the moon's angle in the sky.
