How are freight cars typically differentiated in a train yard?

Answer: C — By their markings, including reporting marks and car numbers

Freight cars in a train yard are primarily differentiated by their markings, which include reporting marks and car numbers. Each freight car is assigned a unique reporting mark that identifies the owner of the car, as well as a specific car number that helps distinguish it from other cars within the same owner's fleet. This system allows for easy tracking and management of cars, ensuring that they can be efficiently sorted and routed based on operational needs. While weight and length, cargo type, and color of the cars can play a role in understanding the characteristics of the equipment, the primary and standardized method for identifying individual freight cars in a yard setting relies heavily on these markings. This identification system is crucial for maintaining accurate records, safety compliance, and operational efficiency within the rail system.