If $\alpha$ is an angle in the fourth quadrant, then
A. $\cos 2 \alpha > 0$
B. $\cos 2 \alpha \leqslant 0$
C. $\sin 2 \alpha > 0$
D. $\sin 2 \alpha < 0$
If $\alpha$ is an angle in the fourth quadrant, then

A. $\cos 2 \alpha > 0$

B. $\cos 2 \alpha \leqslant 0$

C. $\sin 2 \alpha > 0$

D. $\sin 2 \alpha < 0$