Respuesta :
The root cause of the Korean and Vietnam wars was The United States feared the spread of communism in Asia.
The United States did not want Communism spreading in Asia and so was committed to stopping it by any means necessary.
For this reason they went to war to prevent North Korea and North Vietnam which were both communists, from defeating their democratic southern counterparts.
In conclusion, option B is correct.
Find out more on the Korean War at https://brainly.com/question/3542970.