<span>The sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. The parasympatheticnervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.</span>
<em>Answer: Introducing a species into a new environment may have a variety of outcomes. ... However, when these alien species begin to have negative consequences in the new habitat, they are called invasive species. Invasive species may cause environmental harm, economic harm, or impact human health.</em>
Choices 1, 2, and 3 all emit carbon dioxide, not enough to destroy the planet, but they still can cause it over a large amount of time, due to Carbon Dioxide being a greenhouse gas. Therefore, the answer is 4. Bicycles do NOT emit any carbon dioxide at all.