The correct answers are B) North Korea and D) South Korea.
The two countries that are demarcated by the demilitarized zone are North Korea and South Korea.
The demilitarized zone is the border that splits the two Koreans. Geographically it is located at the 38th parallel. This division was created after both countries and China signed the Korean Armistice Agreement. It was signed on July 27, 1953. It is an are full of the military in each side and through the years has been the motive of heavy tension between the two countries and the international community that is afraid of another war conflict.