I believe the correct answer is the last option D.
Explanation:
The volume is 2 1/4 because 1 1/2 times 1 1/2 times 1 = 2 1/4
The instructions then say that there is 8 half unit cubes for every one unit cube so you multiply 2 1/4 by 8 to get 18
I hope this helps :))
