If two parallel planes are cut by a third plane, then the lines of are parallel.
parallelism
transversals
intersections

Intersection. There is only one transversal, and not sure how parallelism would even make sense grammatically. Also, remeber that planes that intersect, intersect on an infinite line. So 2 planes intersecting with another one will form 2 lines. Sine the 2 planes are paralell, but not the same plane, this means there line of intersections will be parallel as well.