Answer:
A) A net is a two-dimensional pattern for a solid.
Explanation:
In fact, a net is a two-dimensional pattern for a solid. But what is a solid? They are three-dimensional shapes. Prisms, cubes, pyramids, among others, are examples of solids. For example, the first figure below is a net because is a two dimensional patter for a pyramid which is shown in the second figure. As you can see, the first figure is a two-dimensional patter for this three-dimensional shape. Hence, by unfolding the pyramid we get the net or, in other word, by folding the net we get the pyramid.