Describe the process of coupling train cars.

The process of coupling train cars is crucial for ensuring that they can safely and effectively operate as a single train unit. The correct answer emphasizes the complete procedure, which involves aligning the cars, adjusting the couplers, and then locking them in place.

First, the train cars must be aligned properly to ensure that their couplers are positioned correctly for connection. Once aligned, the couplers may require adjustments to ensure they fit together seamlessly and function correctly. After this adjustment, the final step is locking the couplers. This locking mechanism is essential because it secures the connection between the cars, preventing them from accidentally uncoupling while the train is in motion.

The importance of locking cannot be understated, as it is a safety feature that keeps the train cars coupled together under the various forces experienced during operation. Other choices do not capture this complete and necessary sequence of events, either by leaving out key actions such as locking or focusing only on parts of the process. Therefore, the outlined process in the correct answer is the accurate and holistic approach to coupling train cars.