Final answer:
Prism T has the greatest volume.
Step-by-step explanation:
To find the volume of each rectangular prism, we need to multiply the number of layers by the number of cubes in each layer.
For Prism R, the volume is 3 x 8 = 24 cubic centimeters.
For Prism S, the volume is 5 x 5 = 25 cubic centimeters.
For Prism T, the volume is 6 x 5 = 30 cubic centimeters.
For Prism U, the volume is 7 x 4 = 28 cubic centimeters.
Therefore, Prism T has the greatest volume.