Question

Brianna is observing a plastic pipe and a styrofoam plate. She notices that the plastic pipe is attracted towards the charged styrofoam plate. What does this most likely tell Brianna about the charges of the two objects?

They have positive charges.
They have negative charges.
They have opposite charges.
The two objects have no interaction.

Answer 1

This most likely tells Brianna that the plastic pipe and the styrofoam plate have opposite charges. When two objects with opposite charges are brought close to each other, they will experience an attractive force, which is what Brianna observed with the plastic pipe and the styrofoam plate.
So the 3rd one