Jet aircraft is mentioned in the passage as an example of ______.

A．an effect of noise on human behavior
B．a person's distance to a noise source
C．a degree of deafness caused by noise
D．a measure of the loudness of sound

A．noise interferes with the task being done
B．noise is a special type of loud sound
C．noise is usually unavoidable in big cities
D．noise can be defined more precisely than sound