Two planes that lie in parallel planes are ________. Answers: Always, Never, or Sometimes

Question

I'm having some trouble on this one... I think it's sometimes...?

Answer 1

sometimes what?

Is there a typo here? The required answer is "always parallel".

actually, the question is ill-worded. What does it mean for a plane to lie in a plane?

I think they mean polygons, or plane figure, or region which lies in a plane.

Associated with a plane is a normal vector, which is perpendicular to it. Parallel planes have normals which have the same or opposite direction. That is, the normals are parallel.