A message signal given by $$m(t)=\frac{1}{2} \cos (\omega_{1} t)-(\frac{1}{2}) \sin (\omega_{2} t)$$  is amplitude modulated with a carrier of frequency $$\omega_{c}$$ to generates $$s(t) = [1 + m(t)] \cos( \omega_{c}t)$$.What is the power efficiency achieved by this modulation scheme?

A

8.33%

B

11.11%

C

20%

D

25%