Which of the following explain why mars does not have a balanced greenhouse effect?
a. mars has an iron-rich core.
b. most of the water is locked in a permafrost layer underground.
c. plate tectonics prevents the release of carbon back into the atmosphere.
d. there are no active volcanoes sending carbon dioxide back into the atmosphere.

Which of the following statements best describes what is occurring in the land surrounding the sahara desert? a desertification is increasing, and the desert is expanding. b. fewer people are trying to farm in this semiarid region. c. the desert is shrinking with the increased use of irrigation. d. increased urbanization has resulted in decreased deforestation. select the best answer from the choices provided mark this and return save and exit next submit