Which statement about the changes in the history of life on earth is correct? a. the theory of plate tectonics explains why the early oceans contained more iron than the oceans contain today. b. the first photosynthetic organisms probably caused worldwide extinctions because they put large amounts of dust into the air. c. geological forces and living organisms have shaped the physical features of the planet. d. the fossil record shows that global temperature changes of only a few degrees have not had much of an impact on living things.