You are presented with the question "Concentrations of what have increased over the last decade dramatically?" and the following answer choices: 
- oxygen
 - harmful substances
 - light
 - greenhouse gases in the air
 - genetic diversity
 - Greenhouse gasses
 - basic building blocks of life
 - ozone

Now knowing that carbon dioxide concentrations in the air have increased over the last decade dramatically and carbon dioxide is a greenhouse gas, choose the best answer.


 

    greenhouse gases in the air     