When light reaches a barrier or the edge of an opening it diffracts, which means that the light

Diffraction is the slight bending of light when it passes around the edge of an object. The amount of bending depends on the relative of the  wavelength of the light wave to the size of the opening. If the opening is much larger than the wavelength the bending will be almost unnoticeable but if the two are equal or closer in length then the diffraction will be noted. Therefore, the correct answer is bends. 

The light slightly "bends" as it goes around the edges of the object. This bending is typically dependent upon the size of the barrier in comparison to the wavelength of the object being diffracted. The more similar in size the two are, the much more noticeable the diffraction tends to be.

It is d, all the other ones say incorrect answer .

The magnets are probably damaged or there not strong enough to attached to the refrigerator