Large cities such as new york and chicago have remained important places for people to live because their

economic opportunity
southern location
warm climate
railroads

a. because the u.s. was the leading with the most technology, economy, etc. also was teamed with other allies witch boosted the economy and materials to improve technology and use it.

he founded the house of wisdom to encourage arabic translation.

hope this is the right answer : ) : )

i liked the part where, i got to pick which statements fitted the questions. i didn't really like doing all the hard work.