17. Given in a circle $\odot O$ with radius 2, the side $AB=2\sqrt{3}$ of the inscribed $\triangle ABC$. Then the degree of $\angle C$ is ).
(A) $60^{\circ}$
(B) $30^{\circ}$
(C) $60^{\circ}$ or $120^{\circ}$
(D) $30^{\circ}$ or $150^{\circ}$
17. C.

From $\sin C=\frac{AB}{2R}=\frac{\sqrt{3}}{2}$, we get $\angle C=60^{\circ}$ or $120^{\circ}$.