Which of the following describes how patterns of magnetic reversals provide evidence of seafloor spreading?

a.
the magnetic polarity on one side of the ridge changes every 5 million years, while the polarity on the other side changes every 10 million years.

b.
the magnetic polarity on one side of the ridge changes every 10 million years, while the polarity on the other side changes every 20 million years.

c.
the magnetic reversal is opposite on either side of the ridge.

d.
the magnetic reversal is the same on both sides of the ridge.