Which of the following is the way in which common markets differ from customs unions?
a) Products, services, and factors of production are allowed to move freely between member countries.
b) Tariffs and non-tariff trade barriers are eliminated when trade and business investments occur between member nations.
c) Member nations share a regulated system of tariff rates and equally distribute tax revenue received from non-member countries.
d) The monetary, tax, and fiscal policies of member nations are overseen by a central authority.