The plastic or metal component that helps protect the fan and channel air through the radiator is the fan:

The correct answer, "shroud," refers to a component designed to enhance the efficiency of the cooling system in a vehicle. The fan shroud serves two main purposes: it protects the fan from debris that could cause damage, while also directing airflow through the radiator more effectively. By channelling the air that the fan pulls in, the shroud ensures that maximum air passes over the radiator's surface, improving the cooling process for the engine.

In contrast, a cover might refer to any protective outer layer but does not specifically channel air or provide the same functionality as a shroud. Housing typically pertains to the structure that contains a component, like the fan or the radiator, but again, does not have the directed airflow properties. A mask is generally not used in automotive terminology in this context, as it usually refers to a protective covering rather than a functional component for air management in the cooling system.