In what way is animation a type of three-dimensional art?

If you mean 2-D animation I suppose it has gravity in affect and persepctive can be drawn to look 3d in a 2d space. As well as 3-D animation being a literal 3-dimensional art form with 3D models and lighting and weight. But there is also stop motion animation that also works with physical 3D models.

a chromatic scale uses the twelve tones of the octave, while a regular scale only uses eight, or seven different notes (as the first note is played twice)