William J. Levitt helped the expansion of the American suburbs by
(A) introducing mass-produced housing developments
(B) creating the Federal Housing Administration
(C) designing an interstate highway system
(D) establishing the installment plan
(E) creating an improved mass-transit system
William J. Levitt helped the expansion of the American suburbs by "(A) introducing mass-produced housing developments" since these developments were relatively affordable, especially for returning veterans.