Answer :
Final answer:
The minimum PSI required for the brake system of a train, as indicated by a gauge or device at the rear, is 90 PSI. This is crucial for the effective and safe operation of the train's braking system. (Option C).
Explanation:
The question pertains to the minimum pressure per square inch (PSI) that the brake system of a train must be charged to, as indicated by a gauge or device located at the rear of the train. This is an important parameter for ensuring the safe operation of train braking systems. According to typical railway operation standards and safety regulations, the minimum PSI the brake system must be charged to is 90 PSI. This ensures that there is adequate pressure throughout the train's brake lines to engage the brakes effectively and safely.. (Option C).
