Josie packed unit cubes into a prism, as shown. Which statement about the volume of the box is true?

Also so, the answer to this is; The volume of the prism is less than 72 cubic units.
Why is this the answer?
The actually cubic units for that is actually 54 cube units which if you think is; 54 < 72
Answer:
The volume of the prism is less than 72 cubic units.
Here's what I did:
6x3x3
Which is length x height x width or it can be the other way around it really doesn't matter I think