Q: You are given a paragraph, with numbered sentences, and a question. Write the numbers of the sentences needed to answer the given question. Separate multiple sentence numbers with a comma (", "). E.g. "1, 2" would be the correct response if Sent 1 and Sent 2 are needed to answer the given question (do not include sentences that contain no information that is necessary to answer the question). Sort the sentence numbers in an increasing order (i.e., '1, 2', instead of '2, 1'). Your answer should not contain anything than the sentence numbers separated by a comma (e.g. '1, 2, 3, 4'). The given question requires more than one sentence to answer. So, your answer must contain at least one comma (", ").
Paragraph- Sent 1: 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 .
Sent 2: 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 .
Sent 3: 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 .
Sent 4: Georgia is assigned to pull the birthday train .
Sent 5: 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 .
Sent 6: During her journey , Georgia breaks down and is taken back to the roundhouse by Doc .
Sent 7: Left behind , Rollo eventually takes Doc 's advice of flagging down one of the other engines returning from their daily runs over the mountain .
Sent 8: Farnsworth and Pete turn down their offers to pull the train .
Sent 9: Meanwhile , Tillie asks the tower to rescue the stranded train , but he insists that Tillie will never do the job .
Sent 10: Jebediah turns down his offer to pull the train because of his age , and returns to the roundhouse .
Sent 11: Chip and Tillie sneak past the sleeping tower and pulls the birthday train up a mountain . 
Question: who assigned to pull the birthday train?.
A:
4.