Trees should be planted everywhere possible. Trees absorb carbon dioxide, a greenhouse gas.

A. Trees, which should be planted everywhere possible, absorb carbon dioxide, a greenhouse gas.

B. Trees should be planted everywhere possible as they absorb carbon dioxide, a greenhouse gas.

C. Trees should be planted everywhere possible to be able to absorb carbon dioxide, a greenhouse gas.

D. Trees should be planted everywhere possible where they absorb carbon dioxide, a greenhouse gas.