The diagram below shows some activity at a mid-ocean ridge. Modified from image courtesy of USGS

Which of the following best describes the process shown in the diagram?
A.
Tectonic plates move closer to each other, which forms magma.
B.
Solid rock liquefies as it reaches the surface and flows outward.
C.
Tectonic plate motion forces magma downward.
D.
Magma moves upward and crystallizes, forming new rock.