Final answer:
Saudi Arabia is a leading oil exporter and gains from specialized trade when the trading price exceeds its opportunity cost, as shown in an economic model shifting from point C to point D, indicating an efficient exchange of Saudi oil for other goods like corn.
Step-by-step explanation:
The original question appears to be missing, but based on the provided context, we know that Saudi oil plays a crucial role in the global economy. Saudi Arabia, a key member of OPEC, holds more than 20 percent of the world's known oil reserves and is the top oil exporter. The country's economy significantly benefits from trade, especially when the trading price, such as exchanging oil for corn with the United States, exceeds their opportunity cost. This is evidenced by a shift from point C to point D in a given figure, where after trading, Saudi oil consumption is at 40 barrels while corn consumption is at 30 bushels, putting them beyond their original production possibility frontier and indicating a clear gain from trade.