The richest source of iron is

Answer: Option B

The richest source of iron is spinach.
A cup of cooked spinach contains about 6.5 mg of iron, which is a fair amount, considering that an average person needs about eight milligrams a day.
Spinach provides many health benefits but very few calories. About 3.5 ounces (100 grams) of raw spinach contain 2.7 mg of iron or 15% of the DV. Although this is non-heme iron, which isn't absorbed very well, spinach is also rich in vitamin C.