Fact 1: Cutting down trees has a negative impact on an ecosystem.

Fact 2: All oaks are trees.

Given the two facts above, answer the question "What has a negative impact on an ecosystem?" with the following options: 
- planting trees
 - cutting down oaks
 - Destroy bridges
 - planting oaks
 - adding habitat
 - deforestation
 - massive damage
 - Pesticides


 

  cutting down oaks       