i really need help with this:

Question

In foreign affairs, perhaps Nixon's greatest accomplishment was
a. abandoning realpolitik, or practical politics
b. bringing about detente with the Soviet Union and with China
c. establishing the People's Republic of China
d. ending the Vietnam War with a resounding American victory

its not D, then wat is it?

Answer 1

I believe a

Answer 2

um...ok thanks

Answer 3

its B