The correct answer would be C. rectangle!
Step-by-step explanation:
When someone is asking for the cross-section shape, they are basically asking for you to cut the shape up (where the 2d figure is) and imagine what the shape would be. For example, if you cut a rectangular prism in half and see what shape it is, it would show a rectangle! This was difficult for me when I first learned it, you'll get the hang of it when you get more practice:)!