Why was the suburb a growing area after the war?
a.
private and quiet
c.
private with access to urban life
b.
loud and busy
d.
complete withdrawal from society

At first, suburban life happen on the top of a landscape that was known as segregated diversity. Later on, many soldiers would come back from the war to "No Vacancy" signs and high cost rents, which ended up in many living with the relatives that they had or recurring to low cost areas.

So, it's not because it was quiet, it's not because it was private and it is not because it was loud. Suburb grew because of a complete withdraw from society, but it was, mostly, not optional, since society was pushing away the veterans and other people with difficulty to the suburbs. The government itself came up with many ways to make it cheaper and easier for those people to build their houses in the suburbs.