What is the key characteristic of diffraction in relation to wave propagation?

Diffraction is a fundamental phenomenon that pertains to how waves, such as light or sound, behave when they encounter obstacles or openings. The key characteristic of diffraction in relation to wave propagation is that it allows waves to bend around obstacles. This bending effect occurs because waves spread out after passing through narrow gaps or when they travel around edges, which can enable them to reach areas that would otherwise be shadowed or blocked.

This property of waves is particularly important in various applications, including communication systems and sound propagation, as it can significantly influence signal behavior in real-world environments. The ability of waves to diffract ensures that they can still reach their destination even when there are physical barriers in place.

In contrast, the other choices do not accurately describe the characteristic of diffraction. Enhancing wave speed, multiplying frequency, and reducing intensity do not relate to the fundamental behavior of waves with regard to obstacles and openings as diffraction does. Understanding this concept is crucial in fields like physics and engineering, where wave behavior is applied in technology and design.