In the mid 1800s democrats believed that a policy of manifest destiny

Would boost the American economy and open up economic opportunities, is the right answer.

Explanation:

Manifest destiny was a publicly sustained faith in the United States during the 19th century. With this manifest immigrants were intended to expand over North America. Democrats used this term in the decade of 1840's to defend the war with Mexico. Moreover, they used this belief to apportion half of Oregon with Great Britain. They strongly believed that this policy of manifest would boost the American economy and open up economic opportunities.

assessment is the missing word

hello! : )

i think a judge or jury, as they preside over the court and is the central figure in a trial.

hope this and i hope i answered in time!

good luck!

~ destiny ^_^