Which statement is correct?

A. The oldest seafloor can be found along a mid-ocean ridge axis.
B. Some magma generated during seafloor spreading spills out onto the surface to produce a new layer of seafloor called gabbro.
C. Some magma generated during seafloor spreading erupts from submarine volcanoes to form basalt.
D. As the seafloor spreads, the lithosphere rises to fill the space between plates.