Using the substitution $u = \sin(2x)$, $\int_{\pi/6}^{\pi/2} \sin^5(2x)\cos(2x)\,dx$ is equivalent to
A. $-2 \int_{1/2}^1 u^5 \,du$
B. $\frac{1}{2} \int_{1/2}^1 u^5 \,du$
C. $\frac{1}{2} \int_0^{\sqrt{3}/2} u^5 \,du$
D. $\frac{1}{2} \int_{\sqrt{3}/2}^0 u^5 \,du$
E. $2 \int_{\sqrt{3}/2}^0 u^5 \,du$