How does it explain the differences between seafloor and continental crust? a. every time a bit of rock is subducted and expelled, its chemistry changes, making it heavier. b. the heavier rock becomes the continental plates, while the relatively unprocessed rocks are the seafloor plates. c. every time a bit of rock is subducted and expelled, its chemistry changes, making it lighter. d. every time a bit of rock is subducted and expelled, its chemistry changes, making it heavier. e. every time a bit of rock is subducted and expelled, its chemistry changes, making it lighter.