If $\overrightarrow{a}$ and $\overrightarrow{b}$ include an angle $120^{\circ}$ and their magnitude are $2$ and $\sqrt{3}$ then $\overrightarrow{a} .\overrightarrow{b}$ is equal to

Question

$$\begin{array}{1 1}(1)\sqrt{3}& (2)-\sqrt{3} \\(3)2& (4)-\large\frac{\sqrt{3}}{2}\end{array}$$