Answer :
Answer: A nuclear accident
Explanation:
The Chernobyl nuclear accident is level 7 (according to the International Nuclear Event Scale), due to the high impact that caused serious consequences on the environment and living beings.
It should be noted that what happened in Chernobyl is considered one of the largest nuclear disasters in human history, because after the accident a large cloud with radioactive particles was found at a high altitude, scattering radiation all over the planet.
Furthermore, it is important to note that although the survival of wildlife in the Chernobyl region has currently been observed and some people still visit the site and others live there, the presence of humans in the place is prohibited.