Which of the following most directly contributed to the developments described in the excerpt?

D. Improvements in production techniques

Explanation:

The 1920s saw an improvement in production techniques that led to the mass production of certain items, chief amongst them the motor vehicle.

People saw the opportunities that mass production could bring and applied it to other products such as radios and the result was a mass production that led to a mass consumption of radio because everybody wanted to own a radio and be connected to the rest of the America and the World.

in 1859, brown and 21 of his followers attacked and occupied the federal arsenal in harper's ferry. their goal was to capture supplies and use them to arm a slave rebellion. brown was captured during the raid and later hanged, but not before becoming an anti-slavery icon. abolitionist and insurrectionist

explanation:

hey

the answer to your question is c the civilian conservation corps

civilian conservation corps

which put thousands of men and women to work for contruction during   1933 to 1942