The Length of the Diagonal of a Box Is Given $D=\sqrt{L^{2}+W^{2}+H^{2}}$

Multiple Choice

The length of the diagonal of a box is given by $D=\sqrt{L^{2}+W^{2}+H^{2}}$ where $L, W$ , and $H$ are the length, width, and height of the box. Find the length of the diagonal, D, of a box that is $1 \mathrm{ft}$ long, $5 \mathrm{ft}$ high, and $4 \mathrm{ft}$ wide. Give the exact value.

A) $2 \sqrt{5} \mathrm{ft}$
B) $10 \mathrm{ft}$
C) $20 \mathrm{ft}$
D) $\sqrt{42} \mathrm{ft}$