Select All of the Following That Are True for Carbon

Select all of the following that are true for carbon dioxide (CO₂) .

A) Plants absorb CO₂ and release O₂ as a by-product.
B) Mars's atmosphere contains a significantly higher percentage of CO₂ than does the Earth.
C) CO₂ contributes significantly to the greenhouse effect.
D) CO₂ currently comprises about 396 parts out of every 1 million parts of the atmosphere.
E) CO₂ is a major component of Earth's atmosphere, but since it is lighter than O₂, it stays in the upper atmosphere.