3. Let $z$ be a complex number, the argument of $z+2$ is $\frac{\pi}{3}$, and the argument of $z-2$ is $\frac{5 \pi}{6}$. Then $z$ equals ( ).
A. $-\sqrt{3}+\mathrm{i}$
B. $-1+\sqrt{3} \mathrm{i}$
C. $-\frac{\sqrt{3}}{2}+\frac{1}{2} \mathrm{i}$
D. $-\frac{1}{2}+\frac{\sqrt{3}}{2} \mathrm{i}$
3. Let $z=x+yi$, it is known that $y>0$. According to the problem, we have $\left\{\begin{array}{l}\frac{y}{x+2}=\sqrt{3}, \\ \frac{y}{x-2}=-\frac{\sqrt{3}}{3},\end{array}\right.$ By dividing the two equations, we get $x=-1$. $\therefore y=\sqrt{3}$, hence $z=-1+\sqrt{3} \mathrm{i}$. Therefore, the answer is B.