President nixon was the first president to: a. visit taiwan b. send troops to vietnam. c. use communist china's official name in public. d. all of the above.

i think it was because of how protected egyptian civilization was was which allowed them to evolve without much outside influence.

a social contract.

"a social contract is an agreement between citizens and their leader where the citizens give up certain freedoms in exchange for protection. the constitution of the united states is an example of a social contract."