Which clause is independent?
a.then we can leave the house. < answer
b.as soon as i find my keys. < answer
c.although my keys might be in my jacket.
d.that i thought i had lost.
need fast.

The correct answer is: America has struggled with its identity as a melting pot due to cultural differences and anti-immigration policies.

The fact America is described as a melting pot means that it gradually evolved from a highly, culturally diverse center to a more homogeneous society holding its own traditions.

During the evolving stage, american citizens conflicted with the arrival of immigrants laborally, socially, and religiously; immigrants were clearly not welcome, and subsequently, popular pressure pushed the congress to pass anti-immigrant policies - restricting the passage of many individuals. This idea is what the text intends to focus on, and it is achieved by presenting an introductory evidence as a means to provide the reader appropiate background knowledge to understand this purpose.