[单项选择]A pioneering study by Donald Appleyard made the surprising discovery that a sudden increase in the volume of traffic through an area affects people in the way that a sudden increase in crime does．Appleyard observed this by finding three blocks of houses in San Francisco that 100ked much alike and had tlle same kind of middle-class and working-class residents, with approximately the same ethnic mix．The difference was that only 2,000 cars a day ran down Octavia Street(LIGHT street, in Appleyard’s terminology)while Gough Street(MEDIUM street)was used by 8,000 cars a day, and Franldin Street(HEAVY street)had around 16,000 cars a day．FranHin Street often had as many cars in an hour as Octavia Street had in a day．
Heavy traffic brought with it danger, noise, fumes, and soot, directly, and trash secondarily．That is, the cars didn’t bring in much trash, but when trash accumulated, residents seldom picked it up．The car, Appleyard determined, reduced the amount of territory residents felt
A. traffic volume on the residents
B. rate of crime on the neighborhood
C. social classes on the transportation
D. degree of pollution on the environment