When a highly coherent beam of light is directed against a very fine wire, the shadow formed behind it is not just that of a single wire but rather looks like the shadow of several parallel wires. The explanation of this involves:

A. Refraction
B. Diffraction
C. Reflection
D. the Doppler Effect
E. an optical illusion

B. Diffraction

Explanation:

Diffraction is the process that occurs when a wave is blocked by an obstacle.The obstacle could be a tiny hole or a much larger object.The waves have to pass through and they usually find a way by bending around the corners of the obstacle or through it depending on the nature and size of the obstacle.

The diffracted rays forms shadow at the back of the obstacle. The shadow is usually made up of several parallel rays.