Why did the military grow so quickly between 1940 and 1941?

The US recruited troops to fight in World War II. This led them to enter into the war. At this point in time the US began mass recruitment of troops to fight the war which led to the military growth and expansion of the United States.

Explanation:

(202 bc - 220 ad) dynasty started by lui bang; a great and long-lasting rule, it discarded the harsh policies of the qin dynasty and adopted confucian principles; han rulers chose officials who passed the civil service exams rather than birth; it was a time of prosperity

the answer to your question is a. the salt plains

in 1811, he led an expedition, known as the george c. sibley expedition, to improve relations with the pawnee and kansa tribes, and also to locate the rumored jefferson's salt mountain