Carbon Dioxide Is Building Up In Our Atmosphere For Two Reasons. The First Is That Many Of Our Activities Actively Produce Carbon Dioxide. The Second Reason Is That Some Of Our Activities Limit The Amount Of Carbon Dioxide That....
He he, the D answer given above is the funniest, but the one they'll want is A. Although it is a simplistic answer.
It's a rarely known fact that old trees actually produce carbon dioxide, not reduce it. It's the younger trees that hoover up CO2. The majority of CO2 absorbed in nature is actually done by blue-green algae, the unsung heroes of the natural world