As Cited in Your Textbook, Which of the Following Best

As cited in your textbook, which of the following best describes why few people in developing countries are affected by dementia?

A) Relatively few people live into late adulthood.
B) Their diets are primarily made of fish, which is high in the B vitamins.
C) They have lower levels of calcium in their diet.
D) There are less environmental teratogens, which are known to cause dementia.