5. Given that $O$ is the circumcenter of acute $\triangle A B C$, points $D$ and $E$ are on sides $A B$ and $A C$ respectively, $\odot O_{1}$ passes through points $B$, $C$, $D$, and $E$, and the circumcircles of $\triangle A D E$, $\odot O_{2}$, and $\odot O_{1}$ both have a radius of 6. Then the distance between $O_{1}$ and $O$ is ( ).
(A) $3 \sqrt{2}$
(B) $4 \sqrt{2}$
(C) $2 \sqrt{3}$
(D) 6
5. D.

As shown in Figure 4, connect $B E$ and $D E$.

Since $\triangle A B C$ is an acute triangle, $\angle B A C$ and $\angle A B C$ are both acute angles.

Given that the radii of $\odot O_{1}$ and $\odot O_{2}$ are equal, and $D E$ is the common chord of the two circles, the minor arcs subtended by chord $D E$ in the two equal circles are equal. Therefore, $\angle B A C = \angle A B E$. Thus, $\angle B E C = \angle B A C + \angle A B E = 2 \angle B A C$. Since $O$ is the circumcenter of $\triangle A B C$, $\angle B O C = 2 \angle B A C = \angle B E C$. Hence, point $O$ lies on $\odot O_{1}$.
Therefore, $O O_{1} = 6$.