The number of solutions of the equation \( (4-\sqrt{3})\sin x-2\sqrt{3}\cos^{2}x=-\dfrac{4}{1+\sqrt{3}},\; x\in\left[ -2\pi,\;\dfrac{5\pi}{2}\right] \) is:
\( 4 \)
\( 3 \)
\( 6 \)
\( 5 \)