Q: Which pair of items will repel each other?
What is the correct answer to this question?

-a positively-charged wool sock and a neutral plastic bag
-a neutral cotton sweater and a negatively-charged plastic pellet
-a negatively-charged balloon and a positively-charged piece of paper
-a negatively-charged plastic strip and a negatively-charged piece of cloth...A:
a negatively-charged plastic strip and a negatively-charged piece of cloth