The answer is the society.
Economics is focused on the problem of the society which is created by a world with limited resources and people with unlimited needs and wants.
D. To improve the lives of others
Church and state were legally separated. A two-party political system was enacted. Jewish men were allowed to serve in the military. Women were granted the right to vote.
We need more info there is no following in you question
Airplanes were vital for ww1 to ease transport of amo and soon guns on the planes including bombs this made it easier for to launch quick air strikes on places like bases vulnerable to air strikes
