How Do Magnetic Stripes on the Ocean Floor Serve as Evidence

How do magnetic stripes on the ocean floor serve as evidence for seafloor spreading?

A) Their symmetry on either side of the mid-ocean ridge shows that new crust is created, then split.
B) Their patterns show that the Earth's magnetic field reverses every few hundred years, on average.
C) They show that island arc volcanism creates new oceanic crust at the mid-ocean ridges.
D) Their symmetry on either side of mid-ocean ridges shows that transform boundaries are sliding boundaries.