What is the greatest difficulty in china?
a: lack of available space b: lack of higher education c: population d: limited natural resourcesi think it's c but i'm not sure. you!

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.

because there are alot of mountains