At what type of plate boundary do plates move apart, resulting in the upwelling of material from the mantle to create new seafloor?
a. subduction
b. divergent
c. convergent
d. transform fault

The correct answer is - b. divergent.

When plates move away from each other (like the North American and Eurasian at the Atlantic Ocean) we have a divergent plate boundary. On this boundaries the Earth experiences the creation of the new crust that has been recycled before from other parts of the world where there are subduction and convergent plate boundaries. If this happens on the seafloor, than we have the rise of underwater mountain ranges, and if it happens on the surface, we have ever growing faults that stretch the land and very often after some time get filled with water from the oceans.

brave new world, aldous huxley (1932)