Final answer:
In Ender's Game, students open their lockers at the Battle School by placing their hand on a sensor and stating their name.
Step-by-step explanation:
The correct way to open a locker at the Battle School in Orson Scott Card's science fiction novel Ender's Game is to put your hand on the sensor and say your name. This high-tech method ensures that only the student to whom the locker is assigned can access it, which is important for maintaining privacy and security in the highly competitive environment of the Battle School. Therefore, the correct answer to how you open a locker at the Battle School in Ender's Game is B. You put your hand on the sensor and say your name.