The integration of the into widespread use during the 1920s most transformed the american economy and culture.
a. car
b. radio
c. toothpaste
d. steam engine

The integration of the radio into widespread use during the 1920s most transformed the American economy and culture, since the radio allowed people to receive both news and entertainment far more easily. 

Opposition to the nra came to a head in 1935, when the conservative supreme court declared the agency unconstitutional, claiming the nra gave the executive branch regulatory powers that belonged exclusively to congress. this decision began a series of court decisions that overturned key elements of the new deal.