It is too simple to say that the Ghost of Christmas Future has the greatest impact on Scrooge because Scrooge breaks down and cries when he sees his own dismal grave and asks for mercy. But by the time Scrooge meets Future, Future doesn't have to do much? It is Marley's ghost that has the greatest impact on Scrooge. Without accepting Marley's visitation, Scrooge would not have changed.
When Marley visits Scrooge, he is still a hardened man who shows no love or human kindness, and even attempts to dismiss Marley, at first, as nothing but a "disorder of the stomach," but soon Scrooge begins to see Marley for who he is, an old tormented friend who has come back to help him, but more so Scrooge sees himself in Marley, and thus the transformation of Scrooge begins.
During Marley's visitation we see Scrooge on his knees begging for "mercy," asking "imploringly" for Marley to "Speak comfort to [him]." And when Marley tells Scrooge to heed him, Scrooge replies by saying he will, but asks Marley not to be "hard upon him! Don't be flowery." And after Marley leaves, Scrooge attempts to say "Humbug," but he can't. All this occurs only hours after Scrooge denies his nephew's invitation to Christmas dinner and tells him that Christmas is a humbug, and after Scrooge denies giving charity to the poor.
Marley has the greatest impact on Scrooge; first, he scares him into believing that he is real; then he warns hims to avoid his evil ways so he can avoid becoming a tormented soul after death, and then has him accept the other ghosts. Without acceptance Scrooge would not have changed.
Although this is generally an opinion question, I think I can safely say that the final ghost of A Christmas Carol (the Ghost of Christmas Future) definitely has the greatest impact on Scrooge. The reason why I say this, not disagreeing with the first responder of course, is that there are significant grunts and complaints made by Scrooge after Marley, the Ghost of Christmas Past and the Ghost of Christmas Present that prove the first three were not able to completely convert Scrooge.
For example, Marley isn't even able to convince Scrooge that ghosts even exist as Scrooge tells himself that Marley's Ghost may have been a simple "complaint" of the stomach. Next, the timeless forceful action of Scrooge using the strange cap of the Ghost of Christmas Past to put out the light of truth. That certainly doesn't speak to conversion. Also, the Ghost of Christmas Present continually asks Scrooge, after Scrooge gives a usual monetary and materialitstic comment, if that is all Scrooge has learned from these visions.
It is only the Ghost of Christmas Future who gets that honor: the honor of Scrooge's full conversion. There is something about seeing a Grim Reaper type figure pointing towards a gravestone with your name that secures the straw that broke the camel's back. It is only after this fourth ghost that we come to "The End of It," and discover the heartwarming change in Scrooge that we all love so well where Tiny Tim "who did not die" exclaims yet again: "God bless us, every one!"
It may be said that each ghost has a significant impact on Scrooge. The Ghost of Christmas Past makes him relive the errors and shame of his youth, and causes him to regret the way he treated his true love. The Ghost of Christmas Present shows him how his present actions cause pain to others, and fill him with pity for Tiny Tim and his family. But when the Ghost of Christmas Yet to Come arrives, Scrooge says he fears him most of all. This spirit shows him his own death, and that of Tiny Tim, and the hateful legacy he leaves behind. It is this vision of the future that forces Scrooge to change his entire outlook and behavior.
u guys r all FAGGETS