You are presented with the question "How has the greenhouse effect changed in the last decade?" and the following answer choices: 
- moved to South America
 - improved
 - Temperature
 - fossil fuels
 - has become cooler
 - worsened
 - climate
 - growth

Now knowing that carbon dioxide concentrations in the air have increased over the last decade dramatically and increases in carbon dioxide make the greenhouse effect worse, choose the best answer.


 

      worsened   