As early as 1815, salt was a ___ in the territory, involving many people and businesses over the years.

i would think it's industries and hydroelectric power

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

the crusaders are identified in the painting;

c. by the red crosses on their backs