What major foreign policy declared that the American continents were no longer open to exploration and settlement by European nations?
A)
The Monroe Doctrine
B)
Proclamation of Neutrality
George Washington's Farewell Address
D
Embargo Act of 1807

Colonization of Canada · Colonization of the United States; Decolonization. P history.svg History portal · v · t · e. Decolonization of the Americas refers to the process by which the countries in the Americas gained their independence from European rule. The American Revolution was the first in the Americas, and the British defeatAfter Rafael del Riego's revolution in 1820  

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.