Use the list to answer the question.
When the Golden Gate Bridge was completed in 1937, it was the world’s longest and tallest suspension bridge.
Completed in 1931, the Empire State Building in New York City has 102 stories. It was the world’s tallest building until 1971.
The Hoover Dam on the Colorado River took six years to complete, from 1930 until 1936, and it is still America’s highest concrete arch dam.
What is the topic of the research paper that these facts will most likely be used in?
why the Hoover Dam was built
the history of skyscrapers
engineering feats in U.S. history
how U.S. architecture has changed