Which part of the train would most likely be affected by power failure during operation?

The control systems of a train are fundamentally critical for its operation, as they manage functions such as speed, direction, and braking. A power failure in the train can lead to a loss of control over these essential systems, creating safety risks and operational challenges. If the control systems become inoperable, the train may be unable to respond appropriately to signals, maintain its speed, or execute necessary maneuvers, which can significantly increase the risk of accidents.

While the brake system, lighting systems, and air conditioning are important components, they typically have backup systems or operate independently of the main power supply to a certain extent. For example, trains may have manual braking systems that can be engaged even if electronic control systems fail, and many also have separate power sources for safety-critical features like lighting. In contrast, the control systems are heavily reliant on electrical power for safe and effective train operation, making them the components most likely to be directly impacted by a power failure.