Given the task definition and input, reply with output. In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Among the entities, try to find the best entity that is most likely to fill in "_" and classify the answers based on options.

Photos of US ambassador to South Korea Mark Lippert meeting with the country's leaders have emerged for the first time since the envoy was attacked by a knife-wielding pro-North Korean activist. Lippert is recovering at Severance Hospital in Seoul, and was able to meet with US Navy Admiral James Winnefeld as well as members of South Korea's ruling and opposition parties. Police are charging the activist, Kim Ki-jong, 55, with murder after he slashed the ambassador while screaming demands for Korean reunification. The attack Thursday on Lippert, at a forum about reunification, prompted rival North Korea to gloat about 'knife slashes of justice,' that left deep gashes and damaged the ambassador's tendons and nerves.Ambassador Mark Lippert injured in a surprise attack at a breakfast meetingKim Ki-jong, a 55-year-old anti-US activist, was immediately arrestedPolice seeking three charges in attack, including attempted murderDoubts over whether he carried out attack alone or was part of conspiracyKim has visited North Korea several times and had books from the countryLippert needed 80 stitches for slash to his face and may have nerve damageHe could be discharged from hospital Wednesday after stitches removed 
 Questions:Stained: Police say the ambassador was about to make a speech when _ pushed him from behind and then started slashing him with a knife. (A) US (B) South Korea (C) Mark Lippert (D) Korean (E) Lippert (F) Severance Hospital (G) Seoul (H) US Navy (I) James Winnefeld (J) Kim Ki-jong (K) North Korea (L) anti-US

(J)