I know jobs for one, over population maybe, and because they are worried that dangerous people could be entering into the country with intention to harm. (unless this is a "only 3 right answer" kind of thing)
Answer Electric Force: force exerted by two charged objects. Positive/Negative Charges: two unlike charges will exert a force that attracts each other while two like charges will exert repelling forces on each other.
Explanation:
