3. The range of the function $y=2 \sin ^{2} x \cos x$ is ( $\quad$ ).
A. $\left[-\frac{4}{9} \sqrt{3}, \frac{4}{9} \sqrt{3}\right]$
B. $[-\sqrt{3}, \sqrt{3}]$
C. $[-2,2]$
D. $[-1,0]$
3. A. $y^{2}=2 \sin ^{2} x \sin ^{2} x\left(2 \cos ^{2} x\right) \leqslant 2\left[\frac{\sin ^{2} x+\sin ^{2} x+2 \cos ^{2} x}{3}\right]^{3}=\frac{16}{27}$, so $-\frac{4 \sqrt{3}}{9} \leqslant y \leqslant \frac{4 \sqrt{3}}{9}$.