A rigid lifesaving device designed for a group of survivors to hold on to while in the water is defined as a _______.

Correct Answer: Option D — buoyant apparatus

A buoyant apparatus is a rigid, non-inflatable lifesaving device designed to support a number of persons in the water. Unlike life rafts, which are enclosed, buoyant apparatuses are intended for survivors to hold onto or cling to until rescue, as defined under USCG lifesaving equipment regulations.