What happened in chernobyl, ukraine, in 1986? a. the explosion of a nuclear reactor killed 30 people. b. deadly gases from a pesticide factory killed 20,000 people. c. the dam holding back a toxic waste retention pond failed, flooding 10,000 homes with benzene. d. uranium seeping out of a mine contaminated the water supply, causing radioactive poisoning in 30% of the city’s residents.