Step 1: Understanding the Question.
The question asks which of the four listed foods is best known as a good source of iron.
Step 2: Key Concept.
Iron in the diet mainly comes from two kinds of foods: animal foods like meat and liver, and dark green leafy vegetables such as spinach, methi, and other greens, which carry the plant form of iron.
Step 3: Detailed Explanation.
Orange is mainly known for its vitamin C content, which helps the body absorb iron better, but the fruit itself is not rich in iron.
Eggs mainly supply protein and some fat, and while they carry a little iron, they are not the food group singled out for iron the way leafy greens are.
Green vegetables are widely recognised in nutrition as one of the main plant sources of iron because of their chlorophyll rich leaves, which carry iron along with other minerals.
Milk is a good source of calcium and protein but is actually low in iron, so much so that infants fed only milk for too long can develop iron deficiency.
Step 4: Final Answer.
Green vegetables are rich in iron, so option (C) is correct.