Country A and Country B have had an informal trading arrangement for many years wherein merchants on the border of the countries may freely trade goods without the restriction offees. Which of the following is true?

• The government of Country A may not arbitrarily begin to charge fees for items brought in from Country B.
• Country A and Country B have a binding agreement to this arrangement under customary international law.
• Country A and Country B have no binding agreement under customary international law.
• More than one response is correct.