The correct answer is that they will repel. Because the balloon turns negatively charged after it gets rubbed on human hair, and the human hair is negatively charged also. That's why the hair flares up after the balloon gets rubbed and then closer to the hair again because opposite charges attract while the same repel.
I'm 100% positive that this is correct, I took the test and this is the most reasonable explanation. Hope this Heeelpps! ^u^