91. The freshwater cooling systems serving the main engines of the platform supply vessel to which you are assigned are arranged as shown in the illustration. What statement best describes the arrangement of the freshwater keel cooler shown in the system diagram

A keel cooler is an external heat exchanger mounted below the waterline to facilitate heat transfer from the engine's freshwater to seawater. The diagram illustrates a closed freshwater loop without a separate seawater circuit, confirming the cooler's external placement.