29. As shown in Figure 12, the areas of the two triangles formed by the diagonals and the two bases of trapezoid $ABCD$ are $p^{2}$ and $q^{2}$, respectively. Then the area of the trapezoid is ( ).
(A) $2\left(p^{2}+q^{2}\right)$
(B) $(p+q)^{2}$
(C) $p^{2}+q^{2}+p q$
(D) $p^{2}+q^{2}+\frac{p^{2} q^{2}}{p^{2}+q^{2}}$
29. B.

Let $A C$ and $B D$ intersect at point $O$. Then $\triangle O C D \backsim \triangle O A B$
$$
\begin{array}{l}
\text { Also, } \frac{S_{\triangle O C D}}{S_{\triangle O C B}}=\frac{q^{2}}{p^{2}} \Rightarrow \frac{O C}{O A}=\frac{O D}{O B}=\frac{q}{p}, \\
\text { hence } \frac{S_{\triangle O W D}}{S_{\triangle O C D}}=\frac{O A}{O C}=\frac{p}{q} \Rightarrow S_{\triangle O N D}=p q .
\end{array}
$$

Similarly, $S_{\triangle O B C}=p q$.
Therefore, $S_{\text {quadrilateral } A B C D}=p^{2}+q^{2}+2 p q=(p+q)^{2}$.