The correct option is D Ukraine
"Chernobyl
disaster" was an accident in 1986 at the Chernobyl nuclear power station in
Ukraine of the Soviet Union. It was the worst disaster in the history of
nuclear power generation. The Chernobyl power station was situated at the
settlement of Pryp’yat, northwest of the city of Chernobyl and north of Kiev, Ukraine.
This disaster occurred on April 25–26, 1986, when technicians at reactor unit
attempted a poorly designed experiment. A large fireball was triggered due to several
explosions. It blew off the heavy steel and concrete lid of the reactor. This
and the ensuing fire in the graphite reactor core released large amounts of
radioactive material into the atmosphere. Many people were died due to
radiations.