How people are moving West during westward expansion

Explanation:

Westward expansion, the 19th-century movement of settlers into the American West, began with the Louisiana Purchase and was fueled by the Gold Rush, the Oregon Trail and a belief in "manifest destiny."

Westward expansion, the 19th-century movement of settlers into the ... Despite this sectional conflict, Americans kept on migrating West in ... and thousands more moved into the Mexican territories of California, New Mexico and Texas. ... ended the Mexican War and added more than 1 million square miles, ...

Explanation:

the answer is d. selective incorporation. (apex)

i would say it is the roman empire europe after the norman conquest.