Final answer:
A rectangular prism with a volume of 72 cubic units can be exactly filled with 72 unit cubes since each unit cube has a volume of 1 cubic unit.
Step-by-step explanation:
To determine how many unit cubes will fill a rectangular prism with a volume of 72 cubic units, we simply need to know how many 1 cubic unit blocks can fit into this space. Since the volume of the prism is given in cubic units, each unit cube is understood to have a volume of 1 cubic unit. Therefore, to find the number of unit cubes that can fill the rectangular prism, we match the volume of the prism with the volume of a unit cube.
The volume of the rectangular prism is 72 cubic units, and the volume of one unit cube is 1 cubic unit. Since volume indicates the total capacity of the prism, the number of unit cubes that can fit into the prism is equal to the prism's total volume in cubic units. Hence, we conclude that exactly 72 unit cubes can fill the rectangular prism.
The correct answer is: