5. A rectangular box has integer length, width, and height, with a ratio of $1: 3: 4$. Which of the following numbers ( ) is most likely to be the volume of the box.
(A) 48
(B) 56
(C) 64
(D) 96
(E) 144
5. D.

Let the length, width, and height of the rectangular prism be $x$, $3x$, and $4x$ $\left(x \in \mathbf{Z}_{+}\right)$, respectively.
Then $V=x \cdot 3x \cdot 4x=12x^{3}$.
If $x=2$, we get $V=96$.