Answer :
Final answer:
When the power supply for the third rail in the subway fails, emergency brakes will engage immediately to ensure passenger safety, and it's possible for lights and other systems to fail depending on the subway system's design.
Explanation:
If the power supply for the third rail in the subway fails, the most immediate consequence is likely to be d. Emergency brakes will engage immediately. In modern subway systems, trains are designed with safety features that are triggered in the event of a power failure. These safety systems are often independent of the main power supply and may operate on a backup power source, such as batteries, to ensure that brakes can be applied even during a power outage. This is a critical feature to prevent accidents and keep passengers safe.
Moreover, while some systems might switch to battery power for certain operations, it is not standard for trains to continue moving solely on battery without the third rail power supply. It is also possible for lights and other less critical systems to fail in the cabin, depending on the design of the subway cars and their backup power capabilities.
