Jacob tells the Losties why he chose them, Jack accepts the role of protector

Around the fire, Hurley, Kate, Jack and Sawyer sit across from Jacob. Hurley asks Jacob why he brought them to the island. Jacob says that he brought them there because he made a mistake, accidentally creating the smoke monster, which could lead to the deaths of all of them and everyone they care about. He says that monster has been trying to find a way to kill him for a long time, so he brought them all there because he would need someone to replace him once the monster succeeded.

Sawyer pipes up and asks why they have to be punished for Jacob's mistake, saying that he was doing fine before he was brought to the island. Jacob says that none of them were plucked from a happy existence. He says that he chose them all because they were flawed and alone like he is. He adds that they all needed the island as much as the island needed them.

Kate then asks why her named was crossed off of the cave wall. Jacob says it was because she became a mother, but adds that it's just a line of chalk in a cave and the job is hers if she wants it. Jack asks what the job is, and Jacob says that the job is to protect a light at the center of the island by making sure it never goes out.

When Sawyer says that the smoke monster (Locke) said that the island doesn't need protecting, Jacob says that it has to be protected from the monster. Jacob adds that they have to do what he could never do, and Jack jumps in asking "You want us to kill him?" and if that's even possible. Jacob says that he hopes they can find a way to kill the monster, because he's certainly going to try and kill them.

Hurley then asks Jacob how he's going to pick, and Jacob says that he's not going to. He adds that he's going to give them what he never had, and that's a choice. Kate then asks what happens if no one takes the job, and Jacob says that "Then this ends very badly." Jack steps forward and says that he'll do it, adding that this is what he's supposed to do. Jacob asks him if that was a question and Jack says "no." Jacob says "Good... then it's time."

This was easily one of the most satisfying scenes of the series. We finally learn why Jacob chose who he brought to the island and he gets to tell the remaining candidates directly. Simply awesome.