3. In parallelogram $A B C D$, $P$ is the midpoint of $B C$. A line parallel to $B D$ through $P$ intersects $C D$ at $Q$. Connect $P A$, $P D$, $Q A$, and $Q B$. Among the triangles in the figure, how many triangles are congruent to $\triangle A B P$ besides $\triangle A B P$ itself? $(A)$ three; $(B)$ four; $(C)$ five; $(D)$ six.
Ans: $[C]$.