People native to islands far from major land masses usually subsist mainly on fish and vegetables, and eat very little red meat. Few of them develop heart disease, and their risk for heart disease does not increase as they get older, unlike people living in less isolated countries. These islanders do often develop heart disease if they move to cities and begin eating diets high in red meat. However, these facts do not prove red meat is the reason they develop heart disease in these instances because __________.

Which of the following most logically completes the passage?

A. such islanders might be genetically predisposed to not contract heart disease
B. people who eat high amounts of red meat in cities of countries that are not isolated tend to develop heart disease
C. some people live in cities of countries that are not isolated and do not develop heart disease
D. other aspects of diet are altered when islanders move to cities such as these
E. red meat provides iron, which is essential for health