Final answer:
A Fully Developed Sea (FDS) is a state where ocean waves have reached their maximum size given certain wind conditions. The development is limited by fetch, the distance over which wind blows across the water, and the duration of the wind's action on the water's surface.
Step-by-step explanation:
A Fully Developed Sea (FDS) refers to a condition on the ocean's surface where the maximum wave size has been reached, given the wind speed, duration, and fetch (the distance over water that the wind has blown). Fetch and duration play significant roles in limiting the development of a fully developed sea. The fetch is crucial because it determines the distance over which the wind can transfer energy to the water; a limited fetch means less space for the wind to work on the water, capping the wave size. Similarly, the duration the wind blows also affects wave development— insufficient duration will prevent waves from reaching their maximum potential size.