Researchers Are Trying to Understand Why the People of Oculus

Researchers are trying to understand why the people of Oculus have such good vision, especially since their ancestors only two generations ago were unusually myopic.Which of the following explanations is the most plausible?

A) Levels of individualism rapidly increased during this time.
B) One generation ago, people starting spending more time outdoors.
C) The education level rapidly increased during this time.
D) One generation ago, people started spending more time swimming.
E) The prevalence of genes for good vision rapidly increased during this time.