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

Ex Input:
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.

Ex Output:
Which statement best explains why the Sun and the Moon appear to be about the same size in the sky?


Ex Input:
A bow wake is created when the wave source moves faster than the wave propagation speed.

Ex Output:
What is created when the wave source moves faster than the wave propagation speed?


Ex Input:
Polarization leads to the buildup of electric charges on objects.

Ex Output:
What leads to the buildup of electric charges on objects?