which is an invention that improved safety for railway passengers?\nrefrigerated rail cars\npullman sleeping…

which is an invention that improved safety for railway passengers?\nrefrigerated rail cars\npullman sleeping cars\ntime standardization\nair brakes
Answer
Answer:
D. air brakes
Brief Explanations:
Air - brakes enhance railway safety by providing more reliable and powerful braking, reducing the risk of accidents. Refrigerated rail cars are for transporting perishables, Pullman sleeping cars for passenger comfort, and time - standardization for scheduling, not directly for safety.