What should be done with freight cars that exhibit defects making them unsafe for movement?

The correct choice emphasizes the critical importance of safety in rail operations. When freight cars exhibit defects that render them unsafe for movement, they must be corrected or set out of the train to ensure the safety of the crew, other trains, and the integrity of the rail infrastructure. This means that any car identified with significant defects is either repaired to meet safety standards or removed from the train to prevent potential accidents or complications during transit.

Addressing safety concerns is paramount in rail operations, as defective cars can lead to severe consequences such as derailments or accidents. Setting out the defective cars helps maintain operational integrity and protects everyone involved in the rail system. This reflects the industry practices and regulations that prioritize safety above all, ensuring trains that are allowed to operate are safe.

In contrast, marking for repair or moving cars to a maintenance area may not address the immediate risks these defective cars pose. Continuing movement with caution does not resolve the underlying safety issues and could lead to serious accidents. Hence, the choice to correct or set out defective cars is the only responsible and safety-oriented action.