A rectangular prism is made of 81 unit cubes. The prism is 9 unit cubes long. Choose two sets of numbers that could be the width and the height of the rectangular prism.
A width: 3 unit cubes
height: 3 unit cubes
B. width: 6 unit cubes
height: 12 unit cubes
C. width: 9 unit cubes
height: 1 unit cube
D. width: 18 unit cubes
height: 4 unit cubes
E. width: 24 unit cubes
height: 3 unit cubes