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

Input: Consider Input: Diffraction is the phenomenon in which light and sound waves become circular at the point source of a barrier.

Output: What is the phenomenon in which light and sound waves become circular at the point source of a barrier?


Input: Consider 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.

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


Input: Consider Input: From viral infections did the first proto-oncogenes arise.


Output: From what did the first proto-oncogenes arise?