Asignificant theme of the monroe doctrine was that
a. slavery should not be permitted in the american territories above latitude 3630'.
b. european powers should refrain from further colonization in the americas.
c. congress is entitled to pass any law to promote the general welfare, except where explicitly barred by the constitution.
d. the united states needs a world-class national university.

Hi there!

A significant theme of the Monroe Doctrine was that...

B. European powers should refrain from further colonization in the Americas.

The Monroe Doctrine was perhaps the most notable achievement of James Monroe's presidency. In it, Monroe declared the Americas off limits from European settlers which included both North and South America. This was to establish the land, and the countries in them, as independent of European rule and was a crucial step towards establishing the U.S. as a power.