So, electric charge can either attract or repel forces. When the objects have opposite charges (for example, one negative and one positive) those two objects will attract each other.
When the two charged objects have the same charge (for example both positive or both negative) they will repel each other.
In this case, the comb is attracting the paper so the charges contain one negative and one positive.
Your answer should be:
"When a comb picks up small pieces of paper, they attract the paper."
