Vitamin \(B_{12}\), also known as cobalamin, is an essential nutrient that plays a crucial role in the formation of red blood cells, neurological function, and DNA synthesis. It is primarily found in animal products because these foods provide the most biocompatible form of vitamin \(B_{12}\).
Among the given options, meat is the richest source of vitamin \(B_{12}\). This is because:
- Meat, particularly red meats, liver, and kidneys, contain high levels of vitamin \(B_{12}\) due to the storage of this nutrient in animal tissues.
- Other animal products like fish, poultry, eggs, and dairy are also good sources, but meat is one of the most potent providers.
On the other hand:
- Green leafy vegetables are rich in other vitamins and minerals, but do not contain vitamin \(B_{12}\) unless they are fortified.
- Corn oil and sunflower oil provide fats and some vitamin E, but they do not contain vitamin \(B_{12}\).
Given this information, the correct answer is meat, making it the most efficient dietary source of vitamin \(B_{12}\).