An explosion at a chernobyl power plant caused radioactive material to spread across the air and land leading to increased cancer risks for nearby people. what is the best explanation for the cause of that explosion?

The accident in Chernobyl was caused by the result of a flawed reactor design and highly untrained staff!

Explanation: In 1986, one of the main core reactors were manned by staff with inadequate training and logical experience which resulted in a steamy explosion with fires that sent 5% of the radioactive reactor core into the atmosphere and down wind.

Not a good few decades for Chernobyl.  

the answer should be true