Fact 1: Planting trees has a positive impact on an ecosystem.

Fact 2: Trees produce oxygen.

Given the two facts above, answer the question "What has a positive impact on an ecosystem?" with the following options: 
- mussels
 - hurricanes
 - invasive species
 - Frogs
 - stay warm
 - animals
 - wildfires
 - oxygen


 

        oxygen 