Answer:
The third option
Step-by-step explanation:
1: 9 cubes
-> Just counting the ones shown!
-> Not even anything, haha
2: 15 cubes
-> 5 * 3 = 15
-> Area of the bottom or top
3: 45 cubes
-> 15 * 3 = 45
-> Volume!
Volume is base times height (base = length times width) so the third option must be correct.
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather