D- volcanic eruptions hope this helps!!
The main U.S. goal in the Southeast Asia War was to protect South Vietnam -- initially from a local communist insurgency and later from conquest by communist North Vietnam. The U.S. also hoped to prevent the spread of communism to other nearby countries. ... The U.S. gave France military assistance in fighting insurgents
Of lack of services/safety, high crime and crop failure.
That statement is true
The lowlands were mainly produced crops that are used to fulfill daily consumption , and the highland got a huge amount of natural resources such as metal and jade
hope this helps