In the new cities of the 1800s, streetcars were to the suburbs and residential neighborhoods as glass and steel were to
a. railroad stations.
b. skyscrapers.
c. palatial mansions of the rich.
d. factories.

A) Railroad stations.
A major reason would be that street cars are not absolutely necessary in a neighborhood but its quit common and it wouldn't be the same without them. But it was something that made a big impact. There's other reasons but this is the best that I an describe it.