you wanted to analyze whether or not the Corps of Discovery (Lewis and Clark's expedition) carried out the plans President Jefferson lays out here, what sorts of documents could you analyze?

corroboration

I think I helped

the answer is c.

hope this : )

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).