(7) The first cable car in New York City was incorporated as part of the design for the newly constructed Brooklyn Bridge, which opened in 1883. Like horsecars, cable cars ran on rails embedded in the streets, but they were powered by steam-driven machines at either end of the line that moved the cars along a long, looped cable. By the early 1900s, however, the introduction of electricity as a power source began to replace steam-powered methods. Trolleys

(8) The development of electricity as a power source in the late 1800s changed the future of transportation. Electric trolleys were smooth, quiet, and emitted less pollution than steam-powered cable cars. Power was fed through cables that ran either above the trolleys or underground through conduits along the trolley track line on the street.

What central idea do the details in paragraphs 7 and 8 support?​

A. Electric power had many more advantages than other forms of power.

B. Steam power made it possible for rails to be safely placed in the streets.

C. Electric-powered cable cars were not considered when the city was originally designed.

D. Steam-powered cable cars were not fast enough to keep up with the demands of a growing city.