Fast plz 20 points carla's new boots came in the shape of a rectangular prism. she made a layer of unit cubes in the bottom of the box. the box was 12 cubes long and 9 cubes wide. she used 7 layers of cubes to fill the box. which of the following statements correctly tells how she can find the volume of the box in cubic units? a. multiply to find the area of the base and then add the number of layers of cubes: (12 x 9) + 7 b. add the width and length of the box, then multiply by the height: (12 + 9) x 7 c. multiply to find the area of the base and then multiply by the number of layers of cubes: (12 x 9) x 7 d. add the width, length, and height of the box: 12 + 9 + 7