International trade - Sources of comparative advantage | Britannica.com
International trade - Sources of comparative advantage: As already noted, British classical economists simply accepted the fact that productivity differences exist between countries; they made no concerted attempt to explain which commodities a country would export or import. During the 20th century, international economists offered a number of theories in an effort to explain why countries have differences in productivity, the factor that determines comparative advantage and the pattern of international trade.
First, countries can have an advantage because they are richly endowed with a particular natural resource. For example, countries with plentiful oil resources can generally produce oil inexpensively. Because Saudi Arabia produces oil very cheaply,
Source of shared Link