Which of these is an important obligation of american citizens

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.

idk lol i just wanna finish mines

social contract theory, nearly as old as philosophy itself, is the view that persons' moral and/or political obligations are dependent upon a contract or agreement among them to form the society in which they live

can someone me with this question:  

1) the end of the conflict between the north and the south didn’t just mark the end of a war; it marked the end of an entire way of life.” which statement best describes what this statement means?  

a) the southerners were no longer free and were controlled by the northern states.

b) the industrial economy in the north was not sustainable.

c) slavery became illegal, which changed completely the south’s labor force and the agricultural economy was destroyed.

d) the states decided to relinquish their independence and return to britain’s rule.