14. As shown in Figure 2, the area of rectangle $A B C D$ is equal to the area of right triangle $D C E$, $A B=5, A D=6$. Then $D E=(\quad)$.
(A) 12
(B) 13
(C) 14
(D) 15
(E) 16
14. B.

From the problem, we know
$$
\begin{array}{l}
S_{\text {rectangle } A B C D}=5 \times 6=30, \\
S_{\triangle C D E}=S_{\text {rectangle } A B C D}=30=\frac{1}{2} D C \cdot C E .
\end{array}
$$

Thus, $C E=12$.
Therefore, $D E=\sqrt{C D^{2}+C E^{2}}=\sqrt{5^{2}+12^{2}}=13$.