Update train_dataset.csv

train_dataset.csv

@@ -6,3 +6,4 @@ What should I do if I see illegal dumping occuring?,"If you see illegal dumping,
 What causes air pollution?," Air pollution comes from fossil fuels, smog, and pollutants such as carbon dioxide, Nitrogen dioxide and sulfur dioxide released into the atmosphere."
 Where can I throw waste legally?,"People can dump their waste legally at solid waste facilities that include landfills, transfer stations, and composting facilities."
 What happens if people illegaly dump waste?,"Consequences for illegal dumping included a fine up to $10,000 and up to six months of jail."
+What causes water pollution?,"The main cause of water pollution includes sewage and waste water, farming, fossil fuel power plants, oil spills, industrial waste and maritime traffic."