Which is an example of a social reason for voluntary migration? the need to expand job opportunities the need to find a cheaper place to live the need to live near extended family the need to escape a depressed area

d. new methods of assembly are introduced.

explanation:

this allows for the goods to be made on a larger scale. not faster because now it is shown to be made better, hence the greater productivity in the question. it is calling for something new to be introduced.

the only other powers were germany russia and uk and they were too busy fighting each other wearing each other down   that the us was becoming strong and they were becoming weaker