paragraph: Eric , a young boy , is excited about his birthday after reading a book and believes that a train will come for him , despite his sister Jill's disbelief .  A few hours later , the train station's control tower wakes up and in the roundhouse , Tillie , a young little blue switcher engine , along with her best bird friend , Chip , wakes up four other trains : Georgia , a kind all-purpose engine , Farnsworth , a stuck-up passenger engine , Jebediah , a worn-out old engine , and Pete , a gruff , burly freight engine .  After the tower assigns Farnsworth and Pete their jobs , Tillie tries to help with the milk train assigned to Jebediah , but the tower insists that she is too small for the job .  Georgia is assigned to pull the birthday train .  A clown named Rollo leads the toys into the train , including Stretch , a basketball player ; Missy , a ballerina ; a Handy Pandy , a panda ; Perky , an elephant ; and Grumpella , a stuffed bird .  During her journey , Georgia breaks down and is taken back to the roundhouse by Doc .  Left behind , Rollo eventually takes Doc's advice of flagging down one of the other engines returning from their daily runs over the mountain .  Farnsworth and Pete turn down their offers to pull the train .  Meanwhile , Tillie asks the tower to rescue the stranded train , but he insists that Tillie will never do the job .  Jebediah turns down his offer to pull the train because of his age , and returns to the roundhouse .  Chip and Tillie sneak past the sleeping tower and pulls the birthday train up a mountain . 
question: What does Tillie ask the tower to do? Who is assigned to pull the birthday train?
answer: Take back Georgia to the roundhouse, Doc