Question: In Java, what is the significance of using the synchronized keyword in method declarations?

A) It ensures that a method can only be accessed by one thread at a time, preventing simultaneous execution by multiple threads.
B) It allows a method to be executed in parallel by multiple threads to improve performance.
C) It marks a method as private, restricting access to only the class in which it is defined.
D) It enables a method to be invoked without requiring an instance of the class, making it a static method.