A box shaped like a rectangular prism has the dimensions: 4 inches by 2 1/2 inches by 2 inches. The box is filled with smaller cubes the same size.

Select the cube that fills the box completely with no gaps or overlaps.

A. 1/7 inch cubes
B. 1/5 inch cubes
C. 1/4 inch cubes
D. 1/3 inch cubes