How are these sources similar? Both blame German aggression for
starting the war.
Both state that imperialism was the most
important cause of the war.
Both suggest that the existence of large
armies contributed to the start of the
war.
Both imply that the assassination of the
archduke was the primary cause of the
war.

Both suggest that the existence of large armies contributed to the start of the war.

Explanation:

It just is.

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

an economic reason that the south needed a reconstruction plan is that plantations, factories, and other businesses were destroyed during the war.