The arrow in the image is pointing to the youngest rock with normal polarity. Normal polarity means that the magnetic field of the Earth is aligned with the present-day magnetic field. Reversed polarity means that the magnetic field of the Earth is aligned in the opposite direction of the present-day magnetic field.
The arrow in the image is pointing to the youngest rock with normal polarity.
Normal polarity means that the magnetic field of the Earth is aligned with the present-day magnetic field. Reversed polarity means that the magnetic field of the Earth is aligned in the opposite direction of the present-day magnetic field.
When new seafloor is created at a mid-ocean ridge, it is magnetized in the direction of the Earth's magnetic field at that time. As the seafloor spreads away from the ridge, it carries this magnetization with it. Over time, the Earth's magnetic field reverses periodically, so the seafloor that was created during one period of normal polarity will be flanked on either side by seafloor that was created during periods of reversed polarity.
The youngest rock with normal polarity is found closest to the mid-ocean ridge, and the oldest rock with normal polarity is found farthest away from the mid-ocean ridge. This is because the seafloor is constantly spreading away from the ridge.
Therefore, the answer is A. Youngest rock with normal polarity.