Read the sentence.

in the late 1800s, a new wave of immigrants, most of whom were unskilled workers looking for jobs in factories, arrived in us cities, and those cities found themselves unprepared to cope with their burgeoning populations.

what kind of sentence is this?
complex sentence
compound sentence
compound-complex sentence
simple sentence

The sentence above is a compound-complex sentence.

Explanation:

A compound-complex sentence is made from two independent clauses and at least one dependent clause. The sentence above contains two independent clauses and two dependent clauses. The difference between an independent clause and a dependent one is that the former can stand on its own as a complete sentence because it represents a complete thought, while the latter can't (see 1 & 2).

1) To cope with their burgeoning populations

2) Most of whom were unskilled workers looking for jobs in factories

1 and 2 are dependent clauses. As such, they can't stand alone as complete sentences, they depend on the main clause.

2 3 and 6 are the answers GG