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.
Answer:
Excess nutrients from fertilizer runoff
Explanation:
The nutrients can create bacteria for the algae
Answer:
a magnification of output
