The following questions refer to the description and figure below.
The figure represents a cross section of the sea floor through a mid-ocean rift valley,with alternating patches of black and white indicating sea floor with reversed magnetic polarities.At the arrow labelled "I" (the rift valley),the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating.At the arrow labeled "III," however,the igneous rock is about 1 million years old,and potassium-40 dating is typically used to date such rocks.Note: The horizontal arrows indicate the direction of sea-floor spreading,away from the rift valley.

-How many other bands of sea-floor crust in the figure have the same magnetic polarity as the crust that directly straddles the rift valley?