The nuclear accident at Chernobyl A.) Was caused by the testing of nuclear weapons
B.) Exposed no humans to radiation
C.) Poisioned large amounts if farmland in Belarus

C "Poisoned large amounts of farmland in Belarus" with radiation

Explanation: On the Saturday 26 April 1986 in modern day Pryp'yat' Ukraine which is located just south of the border of modern day Belarus. The No.4 reactor at the Chernobyl power plant failed due to reactor design flaws and serious breach of protocol during simulated power outage safety test. Causing a major explosion which sent tons of radioactive dust up into the sky poisoning much of the land and people with radiation.