What plane contains points e, f, and h?

The given figure is a rectangular prism. It has 6 faces or 6 planes.
A plane shape, in geometry, is defined as a closed, two-dimensional or flat figure.

The 6 planes are composed of 4 points each.

1.) Plane ABDC
2.) Plane CDHG
3.) Plance ACGE
4.) Plane EFHG  ⇒ This is the plane that contains points E, F, and H.
5.) Plane BDHF
6.) Plane ABFE