Answer:
Higher Population Density
Exposure of Rural children to bacteria
Step-by-step explanation:
According to a new study which had a motive of mapping out children food allergies in th U.S.A, one hypothesis is the high population in the urban areas. This high population often triggers the development of food allergies in children.
Another hypothesis is the exposure of rural children early in life to certain bacteria associated with rural living, Amazingly, this bacteria may protect the children against hereditary hypersensitivity to certain allergens. Whereas, the children who have not been exposed to many bacteria may develop strong allergies to various types of food due to their body's nature.