oil-rich countries in the middle east cover about 4% of earth's total land area but posses about 48% of the world's known oil reserves. what is the main reason for high concentration of reserves in this part of the world?

The correct answer is A. Geological processes.

Explanation

Oil is a hydrocarbon of fossil origin by geological processes that transforms large amounts of organic matter deposited on anoxic bottoms of seas or lake areas of the geological past, which were later covered by heavy layers of sediment. This causes organic materials to be transformed into oil by the heat and pressure of the upper layers. However, this phenomenon does not occur in all parts of the earth because in some, as in the case of the Middle East, there were large amounts of organic matter that became an oil reserve. So the correct answer is A.

the sphincter muscles at the end of the digestive tract is the anus.