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

Fact 2: Forest is largely pine trees.

Given the two facts above, answer the question "what has a positive impact on an ecosystem?" with the following options: 
- animals
 - Frogs.
 - chemical spills
 - Frogs
 - pines
 - parasites
 - pollution
 - mussels


 

     pines    