What is a common feature of a Type I PFD?

A Type I PFD (Personal Flotation Device) is specifically designed for use in rough waters, which is why this is the correct answer. Its primary function is to provide maximum buoyancy and support in situations where water conditions may be challenging, such as strong currents, high waves, or windy weather. Type I PFDs are typically made to keep a person afloat and ensure that their face remains above water, making them suitable for emergencies in unpredictable water environments.

The other options describe different types of PFDs or their uses. For instance, a throwable device is associated with certain life jackets or flotation aids rather than Type I PFDs, which are meant to be worn continuously. PFDs intended for light water sports focus more on comfort and movement, making them different from the robust construction of Type I PFDs. Lastly, Type I PFDs are designed to be worn over clothing, rather than under, as they must fit properly to function effectively in an emergency situation.