How Did the Korean War Finally End

How did the Korean War finally end?

A) The U.S. withdrew its troops unilaterally when the fighting died down.
B) China persuaded the North Koreans to retreat within their own borders.
C) A military deadlock and protracted negotiations finally ended in an armistice that maintained a divided Korea.
D) With the fighting stalemated, the United Nations interposed its own peacekeeping force.