What should the Block Operator not display for a train with a malfunctioning ASC apparatus?

In the context of train operations, particularly with regard to a train that has a malfunctioning Automatic Speed Control (ASC) apparatus, safety is paramount. The display of certain signals can have significant implications for the operation of the train.

When a train's ASC is malfunctioning, it indicates that there may be an inability to properly govern speed control and ensure the safe operation of the train. As a result, the Block Operator must avoid displaying any signals that suggest the train can proceed at normal or higher speeds, which might be dangerous without the operational ASC.

In this situation, signals such as "Absolute Clear," "Absolute Medium Clear," and "Flashing Slow Approach" could imply that the train is permissible to move forward under potentially unsafe conditions. "Absolute Clear" indicates no restrictions for the train, while "Absolute Medium Clear" allows for a moderate speed; both are inappropriate for a train without functioning ASC. "Flashing Slow Approach" signifies a warning for the train to prepare to slow down but still suggests that it can continue moving forward.

Given this information, the Block Operator should not display any of these signals for a train with a malfunctioning ASC apparatus, as they could contribute to unsafe operation. Therefore, the correct answer embodies the necessity for caution