Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

A(n) gastropods is noted for having its eyes at the tips of stalks or tentacles that emerge from its head.
What type of creature is noted for having its eyes at the tips of stalks or tentacles that emerge from its head?

The sun and the moon appear to be about the same size in the sky because the moon is smaller in diameter and is closer to earth than the sun.
Which statement best explains why the Sun and the Moon appear to be about the same size in the sky?

Because the current is alternating, the magnetic field of the iron core keeps doing reversing.

Because the current is alternating, the magnetic field of the iron core keeps doing what?