$$\tan 960^{\circ} + \cos 510^{\circ} + \sec 750^{\circ} =$$

A

$$\frac{7 -\sqrt{3}}{2\sqrt{3}}$$

B

$$\frac{10 -\sqrt{3}}{2\sqrt{3}}$$

C

$$\frac{7}{2\sqrt{3}}$$

D

$$\frac{13}{2\sqrt{3}}$$