Why did we structure the telephone system to use switching offices?

A.because when telephones were first invented, they came in pairs of two, and customers had to string a single wire between them to connect them; soon the cities were covered with wires passing over houses and trees in a wild jumble

B.because Bell Telephone Company invented the switching office, and the company was a monopoly at the time, who made this a standard

C.because the switching office was more profitable than using a tandem office or an interoffice trunk

D.none of the above