PART B: Which detail from the text best supports the answer to Part A?

A
“Sometimes, though, people have more urgent reasons to leave their home countries.” ( Paragraph 2)
B
“In just a few years after the discovery of gold, about 150,000 Chinese people immigrated to the United States.” ( Paragraph 4)
C
“Over the years, countries have used laws, both fairly and unfairly, to control immigration.” ( Paragraph 6)
D
“One reason for the global growth of immigration is the improvement of transportation and the decrease in cost.” ( Paragraph 8)