When Obito heard Rin say that even she did not know who had revived her, he exclaimed in surprise, "You don't know either? That doesn't make sense!" He simply could not understand it. Whoever had revived Rin must have wanted to use her for something, most likely against him or Kakashi. But targeting Kakashi did not quite hold up, since Rin had died to Kakashi's Chidori. Whoever had revived her should have known about that history, so Obito was the only likely target. Yet Itachi had only recently learned his secret, and only a few of Konoha's higher-ups knew about it.
"Could it have been Konoha's higher-ups?" Obito wondered suspiciously. "Yes, that's certainly possible. Besides, Konoha has the Impure World Reincarnation Jutsu, so they're the most likely suspects. But judging by your reaction, Kakashi, you didn't know about Rin. That means the Hokage wasn't behind this. Could it have been Danzo?"
Hearing Obito mutter to himself, Kakashi said, "No, it wasn't Danzo. He probably still doesn't know you're Obito, and he has no reason to target you. Besides, whoever revived Rin didn't control her. That suggests they had no ill intentions. After thinking it over, there's only one person I consider the most likely suspect."
Obito turned toward Kakashi in confusion, while Rin also looked at him curiously, hoping he could tell her who had revived her. Seeing their curious faces, Kakashi did not keep them in suspense. "Naruto Uzumaki, my dear student-and our teacher's son."
"What? Naruto Uzumaki? How could it be him? Why would he revive Rin? What is he after?" Obito asked, his initial surprise giving way to worry.
Obito could never have imagined that Naruto Uzumaki had revived Rin without controlling her to kill him. As far as Obito was concerned, he had caused the deaths