How did the U. S. plan on upholding the Monroe Doctrine?

A) With help from other nations
B) Through threats to foreign nations
C) Through negotiations only
D) With force if necessary

How did the construction of the erie canal improve transportation in the united states in the 1820s? a. the canal connected the great lakes to the mississippi river. b. the canal connected the great lakes to the ohio river. c. the canal connected the atlantic and pacific oceans. d. the canal connected the great lakes to the atlantic ocean.