Answer:
The intersection of the horizontal plane with the prism would have a square shape.
Step-by-step explanation:
A right rectangular prism is one in which each side makes an angle of with its base, which is a square. It is a three dimensional figure with six faces.
The point where the horizontal plane and the prism coincides would take the shape of the base of the prism. This is because the prism rests with its base on the horizontal plane. Thus, the shape required is in the form of a square since its base is a square. The length and width of its base are equal.