Why is the cell theory considered a scientific theory? a. it was proposed by several scientists. b. it is an explanation that is well supported. c. it has always been proven to be correct. d. it was formed over 100 years ago.

Why are carbon dioxide concentrations expected to increase? a carbon dioxide concentrations are expected to increase, because fossil fuel burning is expected to increase b. carbon dioxide concentrations are expected to increase, because of an increase in agriculture. c.carbon dioxide concentrations are expected to increase, because more land will have to be cleared for increasing populations and agricultural use. d. all of the above select the best answer from the choices provided mark this and return save and exit next submit submit