函数 $y=2 \tan \left(3 x+\frac{\pi}{6}\right)$ 的定义域是
$\text{A.}$ $\left\{x \left\lvert\, x \neq \frac{\pi}{2}+k \pi\right., k \in \mathrm{Z}\right\}$
$\text{B.}$ $\left\{x \left\lvert\, x \neq \frac{\pi}{12}+k \pi\right., k \in \mathrm{Z}\right\}$
$\text{C.}$ $\left\{x \left\lvert\, x \neq \frac{\pi}{6}+\frac{k \pi}{3}\right., k \in Z\right\}$
$\text{D.}$ $\left\{x \left\lvert\, x \neq \frac{\pi}{9}+\frac{k \pi}{3}\right., k \in \mathrm{Z}\right\}$