Question: What is the effect of declaring a method as synchronized in Java?

A) It ensures that the method can be accessed by only one thread at a time within an entire application.
B) It ensures that the method can be accessed by only one thread at a time for each instance of the class.
C) It allows multiple threads to execute the method simultaneously, improving performance.
D) It prevents the method from being overridden by subclasses, enforcing immutability.