The united states "wound down" its war involvement by transferring fighting from american to south vietnamese troops, a process that was called

That process was called VIETNAMIZATION.

President Nixon was the one who instituted the Vietnamization policy, which  emphasized that the United States must empower South Vietnamese forces to assume more combat duties.

By the time the US was shifting emphasis to this sort of policy, it was too late to stave off the victory of the North Vietnamese and Viet Cong forces.  The US eventually withdrew its forces from Vietnam in 1973, and by 1975, Saigon (in South Vietnam) fell to the North Vietnamese communist forces.

b. they tried to evict the squatters from the area.

so sorry if wrong

answer: the time zones used to be whatever the local authority wanted them to be. one town might have 6am whenever the sun came up and another town had 6am 10 minutes later.  

the trains had a hard time when their orders said to be at a certain point at 6am.  

6am, but who's 6am.  

the railroads got together and set the time zones more or less along the longitude lines across the country.

explanation: