What does the third level refer to?​

well, number 1, the 1920s was not economically prosperous until the start of the lend-lease act, which employed large amounts of people in producing equipment for the allies.

b. world war ii is your answer, because wwi had already ended at 1918, and the cold war was after 1945.

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the answer is a because the astrophel does more and sidney goes to the astrophel more than stella.