Scientist Ram Oren is of the opinion that common beliefs of the tree' s ability to absorb carbon dioxide are ______.

A．They broke down and the main parts turned into oxygen.
B．They broke down and the carbon content had mainly turned into carbon dioxide.
C．They broke down and the carbon content was mainly absorbed in the soil.
D．They absorbed more carbon dioxid

A．6) probably refers to ______.A. carbon dioxideB. nitrogenC. atmosphereD. coal