You are presented with the question "what have a negative impact on the environment" and the following answer choices: 
- harmful substances
 - groundwater contamination
 - harvesting
 - fish
 - major threat to health
 - Sulfur dioxide
 - storms
 - Greenhouse gases

Now knowing that landfills have a negative impact on the environment and landfill leachates and groundwater contamination, choose the best answer.


 

  groundwater contamination       