The magnetic north and south poles of Earth are interchanged.
Explanation:
Earth acts as a huge bar magnet due to the presence of iron and nickel in its core. The magnetic field surrounding Earth is known as magnetosphere which constantly protects from solar wind. Auroras are visible in the sky when charged particles from the sun interact with the magnetic field of the earth especially near the poles where strength of the magnetic field is maximum.
Over the years, the magnetic field might weaken as it is continuously repelling the charged particles from the Sun. As a consequence, the poles of this magnetic field might reverse.
Thus, changes in Earth's magnetic field can reverse the poles.
The only statement that makes sense as to which one describes an effect of changes in Earth's magnetic field is the first one - <span>Southern lights are seen at high altitude places like Alaska. Normally, Southern lights are seen around the South Pole, which means that it is quite odd for them to be seen in Alaska, which is near the North Pole.</span>
