@azk, dude i still think the answer is C, here is the wiki link, hope it helps
Reference counting - Wikipedia, the free encyclopedia
Reference counting is often known as a garbage collection algorithm where each object contains a count of the number of references to it held by other objects. If an object's reference count reaches zero, the object has become inaccessible, and it is put on a list of objects to be destroyed.
Simple reference counts require frequent updates. Whenever a reference is destroyed or overwritten, the reference count of the object it references is "decremented", and whenever one is created or copied, the reference count of the object it references is "incremented".
cheers!:tup: