What happens when an object's reference count is zero?

When an object's reference count is zero, it means that there are no remaining references to that object in the program. This situation indicates that the object is no longer reachable or usable by the application. Once an object is no longer referenced, it is eligible for garbage collection or deallocation by the memory management system, which recovers the memory occupied by the object. Therefore, recognizing that an object is no longer referenced is a critical aspect of memory management in programming languages that utilize reference counting as part of their garbage collection strategy.

The other options do not accurately describe the implications of a reference count being zero. For instance, saying the object will be deallocated from memory immediately doesn't consider the deferred nature of garbage collection, which might not happen instantly. Similarly, stating that the object is being referenced is contradictory when its reference count is zero, and saying the object is ready for memory allocation is irrelevant, as it implies it is still in use.