Use unit cubes to find the volume of the rectangular prism.
A. 12 cu. un.
B. 45 cu. un.
C. 36 cu. un.
D. 40 cu. un.
To find the volume of the rectangular prism, we need to count the number of unit cubes that can fit within it.
Looking at the provided options, the only possible answer that is a factor of 10 (which is the number of cubes we see in the picture) is 40 cu. un.
Therefore, the answer is option D. 40 cu. un.