Richard nixon set out to do what previous presidents had tried to do in vietnam. that is, nixon wanted to a)  unite north vietnam and south vietnam b)  get bao dai to become leader of south vietnam c)  keep south vietnam as an independent, non-communist nation d)  divide vietnam into cochin china, annam, and tonkin

D) divide Vietnam into Cochin China, Annam, and Tonkin

Explanation:

He had the Vietnamization plan, a plan to train Vietnamese soldies.

Different from previous presidents, Nixon wanted no longer to fight communism, but yes to find a cooperative world order, including if needed, the division of Vietnam.

So the correct answer is:

D) divide Vietnam into Cochin China, Annam, and Tonkin