The introduction of which of the following most contributed to declining automobile prices during the 1920s?
protective tariffs
consumer advertisements
installment plans
assembly lines

Respuesta :

(D)Assembly lines. 
When an item can be quickly mass produced, it will become easier to create faster. The price will drop because the supply will grow.
Assembly lines allowed cheap cars for the public. Assembly lines also helped hire low skilled people. They had one job which was to put one piece on the car.