Scientists believe that early plants released oxygen in a process called photosynthesis. Where did the carbon dioxide needed for photosynthesis come from in the early atmosphere?
A)
Volcanoes released carbon dioxide
B)
The Earth captured carbon dioxide from space with its gravity.
C)
Water molecules on the Earth were broken to release carbon dioxide.
D)
Early bacteria and plants released carbon dioxide as well as oxygen when
they performed photosynthesis

Early bacteria and plants released carbon dioxide as well as oxygen when they performed photosynthesis. because bacteria could have been aerobic back then and released carbon dioxide for the plants to use in photosynthesis.

Hope this helps

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.