Pick from:
I. disease;
II. viruses;
III. A virus;
IV. Carbon;
V. tar;
VI. toxins;
VII. herbicide;
VIII. vehicles;
Q: Fact 1: Cutting down trees has a negative impact on an ecosystem. Fact 2: If trees are cut or burned, the carbon is released back into the atmosphere. Given the two facts above, releasing what can have a negative impact on an ecosystem?
A:
IV.