Answer:
cube
Step-by-step explanation:
The shape in the middle of the two rectangular prism would be a cube. This is the case since the angle at the base of the rectanglular prism forms a 90-degree angle. This indicates that the line is a straight line and would also form a 90-degree angle with the bottom angles as well. This would ultimately indicate that it forms a square, and since the shape is a 3-Dimensional shape it would be classified as a cube in this image.
