[Solved] Why is the Moon not completely invisible (it appears as a very deep red color)to the naked eye during a total lunar eclipse? Retail Market: The part of the economy that deals with the sale of goods or services directly to consumers, encompassing a wide range of businesses and stores. OPEC Nations: Member countries of the Organization of the Petroleum Exporting Countries, a group that coordinates the petroleum policies of its members to secure fair and stable prices for petroleum producers. Supply Curve: A graphical representation showing the relationship between the price of a good and the quantity of the good suppliers are willing to sell. Mass Transit: Public transportation systems that move large numbers of people within urban and suburban areas.