To determine the 20th-century event during which the image in question would have been found, additional context about the image itself is needed. However, I can provide some general information about each option:
A. The Korean War (1950-1953) - This conflict was fought between North and South Korea, with involvement from international forces, including the United Nations and China.
B. The Vietnam War (1955-1975) - A prolonged conflict in Vietnam, involving North Vietnam and its communist allies against South Vietnam and its principal ally, the United States.
C. Japan's "Nanking Massacre" (1937-1938) - A mass murder and war rape by Japanese troops against the residents of Nanjing (formerly Nanking), the former capital of China, during the second Sino-Japanese War.
D. China's "Cultural Revolution" (1966-1976) - A sociopolitical movement initiated by Mao Zedong to preserve communist ideology in China, which led to widespread social, political, and economic upheaval.
If you provide a description or details about the image, I would be able to better match it to one of these events.