3. In the rectangular prism $A B C D$
$$
\begin{array}{l}
-A_{1} B_{1} C_{1} D_{1} \text {, } A B_{1} \\
=2 \sqrt{2}, A D_{1}=\sqrt{17} .
\end{array}
$$

Then the range of $A C$ is ( ).
(A) $\sqrt{17}-2 \sqrt{2}<A C$ $<5$
(B) $3<A C<\sqrt{17}+2 \sqrt{2}$
(C) $3<A C<5$
(D) $\sqrt{17}-2 \sqrt{2}<A C<\sqrt{17}+2 \sqrt{2}$
3. C

Obviously, $A C=B_{1} D_{1}$, and the necessary and sufficient condition for $\triangle A B_{1} D_{1}$ to be an acute triangle is
$$
\sqrt{A D_{1}^{2}-A B_{1}^{2}}<B_{1} D_{1}<\sqrt{A D_{1}^{2}+A B_{1}^{2}} \text {. }
$$

Thus, $3<A C<5$.