Which best describes what happens to sunlight after it passes through the keyhole of a door? a) it converges until one particular shadow region b) it spreads out into multiple shadow regions c) it bends back toward the door d) it scatters back toward the door

How is that?

Diffraction happens when a wave (mechanical or electromagnetic wave) meets an obstacle or a slit .

When this occurs, the wave bends around the corners of the obstacle or passes through the opening of the slit that acts as an obstacle, forming multiple patterns with the shape of the aperture of the slit.

Note that the principal condition for the occurrence of this phenomena is that the obstacle must be comparable in size (similar size) to the size of the wavelength.

Now, if we assume the sunlight as an electromagnetic wave that passes through the keyhole of a door (obstacle), this light will scatter and multiple shadow regions with the shape of the keyhole will be formed.

Therefore, the answer is B:

it is very well related to a lot of things but with my limited knowledge i can confidently say that the answer is space.

the part of the wave he is travelling on is the crest