Question: Which of the following statements about Java's concurrency model and thread safety is correct?

A) The synchronized keyword ensures that only one thread can access a method at any time, but it does not provide visibility guarantees for shared variables.
B) Immutable objects in Java are inherently thread-safe because their state cannot change after construction.
C) The ReentrantLock class provides a simpler alternative to synchronized blocks with no additional features.
D) Using the ThreadLocal class allows multiple threads to share the same instance of a variable.