It is a rectangle which is similar to the base.
It is a rectangle which is similar to (but smaller than) the rectangular base.
A prism can have a triangular cross-section with a rectangular base
A circle.
It depends on the pyramid. If it is a square based pyramid, a horizontal plane will give a square cross section, a plane inclined by a rotation parallel to one of the base axes will give a rectangular cross section whereas a plane inclined by rotation along both basal axes will result in a parallelogram cross section. Not sure how you get a parallelogram from a pentagonal or hexagonal (etc) pyramid.
trapezoid
It is a rectangle which is similar to the base.
triangle
It is a rectangle which is similar to (but smaller than) the rectangular base.
A triangular prism has a uniformed cross-section whereas a rectangular pyramid does not.
A rectangular prism has the same cross section throughout its length, a pyramid doesn't however
A prism can have a triangular cross-section with a rectangular base
A circle.
It depends on the pyramid. If it is a square based pyramid, a horizontal plane will give a square cross section, a plane inclined by a rotation parallel to one of the base axes will give a rectangular cross section whereas a plane inclined by rotation along both basal axes will result in a parallelogram cross section. Not sure how you get a parallelogram from a pentagonal or hexagonal (etc) pyramid.
cone, cylinder, rectangular prism, square pyramid and triangular prism
A cylinder has a circular cross section, a rectangular prism has a rectangular cross section.
A rectangular prism has a rectangular cross section whereas a cylinder has a circular cross section