Which phenomenon can occur when the fetch and wind strength are optimal in wave development?

The phenomenon that occurs when the fetch and wind strength are optimal in wave development is swell. Swell refers to a series of waves that have traveled out of their area of generation after being driven by consistent winds over a lengthy distance, known as fetch. When the fetch is long enough and the wind is strong and consistent, it generates larger, better-organized waves that can travel vast distances across the ocean.

Swell can be recognized by its smooth, rounded waves that are more regular and have a longer wavelength compared to those generated by local storms. This is in contrast to choppy or chaotic waves that might arise under less favorable conditions.

Other options such as rogue waves are unusually large waves that can appear suddenly and are not directly related to conditions of fetch and wind strength. Destructive interference involves the overlapping of waves that leads to a reduction in wave height, while surf beat refers to the oscillating pattern of wave heights caused by the interaction of different wave groups. None of these phenomena align with the specific conditions of optimal fetch and wind strength that produce swell.