A message m(t) bandlimited to the frequency fm has a power of Pm. The power of the output signal in the figure is

A

$$\frac{(P m \cos \theta)}{2}$$

B

$$\frac{(P m \sin^{2} \theta)}{2}$$

C

$$\frac{Pm}{4}$$

D

$$\frac{(P m \cos^{2} \theta)}{4}$$