Which tectonic boundary results when two tectonic plates pull apart from each other?

What did the pattern of earthquakes in the wadati-benioff seafloor zones show scientists? a.) earthquakes occur where the ocean floor reaches its highest temperatures. b.) many earthquakes take place 700 kilometers below the seafloor. c.) slabs of ocean floor return to the mantle in subduction zones. d.) ocean - trenches cause earthquakes.