Final answer:
The increase in the GNP in the United States in the 1920s was mainly driven by the industry and technology sectors, as well as the building and construction industry. The correct answers are second and third options.
Step-by-step explanation:
The sectors that were most responsible for the increase in the GNP (Gross National Product) in the United States in the 1920s were industry and technology as well as building and construction.
The automobile and home appliance industries experienced significant growth during this time period, leading to an increase in production and employment opportunities. Additionally, advancements in technology, such as electrification, contributed to the growth of industries and the overall economy.
With electrification reaching more homes, companies such as Westinghouse and General Electric grew significantly, bolstering the GNP with the increased production of electrical appliances. New consumer products like radios and recreational services such as going to the movies also became popular, supported by a booming tourist industry driven by the wider availability of automobiles.
The construction sector also contributed to economic growth, as new homes required appliances, furniture, and various other consumer goods, and new roads needed to accommodate the increasing traffic from cars. However, sectors like farming and agriculture did not experience the same level of prosperity and were faced with struggles due to price declines and overproduction.