3. Given a right triangle with a perimeter of 14, and the median to the hypotenuse is 3. Then the area of the right triangle is ( ).
(A) 5
(B) 6
(C) 7
(D) 8
3. C.

Since the median to the hypotenuse is 3, the hypotenuse is 6. Let the lengths of the two legs be $a$ and $b$. Then
$$
\begin{array}{l}
\left\{\begin{array}{l}
a+b=8, \\
a^{2}+b^{2}=36
\end{array}\right. \\
\Rightarrow 2 a b=(a+b)^{2}-\left(a^{2}+b^{2}\right)=28 .
\end{array}
$$

Thus, $S=\frac{1}{2} a b=7$.