If $\sin\alpha = \dfrac{\sqrt{3}}{2}$ and $\dfrac{\pi}{2} < \alpha < \pi$, then $\alpha$ equals —

• a$\dfrac{\pi}{3}$
• b$\dfrac{2\pi}{3}$
• c$\dfrac{4\pi}{3}$
• d$\dfrac{5\pi}{6}$