Final answer:
The Douglas Aircraft Company, Selective Service Act, WAVES, and Thunderbirds are all related to the mobilization for World War II, which significantly boosted the American economy and led to the production of military equipment and drafting of soldiers for the war.
Step-by-step explanation:
The Douglas Aircraft Company, Selective Service Act, WAVES, and the Thunderbirds all have a connection with the World War II era. The Selective Service Act was legislation for drafting soldiers, which was prominent during World War II. The Women Accepted for Volunteer Emergency Service (WAVES) was a division of the U.S. Navy, where women could enlist to serve during the war period.
The Thunderbirds, an aerial demonstration team, were formed after World War II, but their creation was a direct result of advanced flight training and experience gained during the conflict. Lastly, the Douglas Aircraft Company became a major defense contractor during World War II, producing numerous aircraft for the war effort.
Therefore, all these elements belong to the time period of mobilization for World War II, which pulled America out of the Great Depression, restored full employment, converted American factories to wartime production, and significantly boosted the economy.