Final answer:
The volume of the box is 30 cubic inches, as it holds two layers of 15 cubes each, with each cube having a volume of 1 cubic inch.
Step-by-step explanation:
To find the volume of the box that holds Stephanie's 30 cubes, we consider that each cube has a side of 1 inch. Since there are 2 layers with 15 cubes each, we first calculate the volume of one layer. Each cube being 1 inch on each side has a volume of 1 cubic inch, and so 15 cubes in one layer have a combined volume of 15 cubic inches. Assuming that the arrangement of cubes is such that it defines the base of the box, the dimensions of this base layer would be the combined length and width of all cubes placed side by side.
However, without more information about the exact arrangement, we cannot conclude the length and width as the cubes could be arranged in different ways. But we can calculate the total volume by knowing there are two layers. Hence, two layers would have a combined volume of 2 x 15 cubic inches, which is 30 cubic inches. Since the box can hold both layers perfectly, the volume of the box must also be 30 cubic inches.
Therefore, the correct answer is a) 30 cubic inches.