8. The polar equation of a circle is $\rho=\sqrt{2}(\cos \theta+$ $\sin \theta$ ), the coordinates of the center of the circle are ( ).
(A) $\left(2, \frac{\pi}{4}\right)$
(B) $\left(1, \frac{\pi}{4}\right)$
(C) $\left(1, \frac{3 \pi}{4}\right)$
(D) $\left(\sqrt{2},-\frac{\pi}{4}\right)$
8. (B).

Transform the equation of the circle into Cartesian coordinates, we get
$$
\begin{array}{l}
x^{2}+y^{2}-\sqrt{2} x-\sqrt{2} y=0, \\
\text { i.e., }\left(x-\frac{\sqrt{2}}{2}\right)^{2}+\left(y-\frac{\sqrt{2}}{2}\right)^{2}=1 .
\end{array}
$$

The center of the circle is $\left(\frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2}\right)$, with a radius of 1. Converting to polar coordinates, we get
$$
\left(1, \frac{\pi}{4}\right) .
$$