What is diffraction?

Diffraction is a phenomenon that occurs when waves encounter an obstacle or a slit that is comparable in size to their wavelength. This interaction causes the waves to change direction and bend around the edges of the obstacle or through the slit. As a result, diffraction can lead to a spreading out of waves, which is most commonly observed with light and sound waves.

In the context of light, diffraction is important in various applications, such as in the design of diffraction gratings and understanding the behavior of light in optical systems. It highlights the wave nature of light, which is critical in understanding advanced topics in physics and engineering. The correct answer accurately reflects this fundamental aspect of wave behavior.

Other choices focus on different wave behaviors but do not encapsulate the concept of diffraction. For example, while sound wave propagation is relevant to waves, it does not define diffraction itself. Similarly, light absorption and reflection describe different interactions of waves with matter and surfaces, which do not involve the bending and spreading characteristic of diffraction.