Over the summer break, Jed earns extra cash working as a salesman at Sensational Sound Systems. As one of the most knowledgeable salesmen on staff, Jed tells a young couple shopping for a sound system that the more expensive models are worth the money because they ____.
a. amplify sound up to 160 dB
b. filter out frequencies below 10000 Hz
c. boost frequencies below 80 Hz
d. buffer sounds that reach 60 dB
