Inhabitants of a Small Island Off the Coast of Georgia

Multiple Choice

Inhabitants of a small island off the coast of Georgia have an extremely high rate of type II diabetes. Researchers studying the cause of the high rate noted that all sufferers of type II diabetes on the island ate palm oil everyday, while healthy people ate it at most a few times per month. The researchers concluded that eating palm oil caused the type II diabetes.
Which one of the following, if true, would most strengthen the researcher's reasoning?

A) Most of the healthy adults never ate palm oil at all.
B) In areas off the island, palm oil consumption is associated with high levels of heart disease.
C) When placed on a palm-oil free diet, sufferers of type-II diabetes show fewer symptoms of the disease and in many, the disease goes away completely.
D) Palm oil is not common in the traditional foods of the region and has only recently become popular due to its low price.
E) Non-natives who move to the island also exhibit higher rates of type II diabetes than do people off the island.