In developed nations people have more fast food options which lead to cardiovascular disease. As well as screen time all day since this is one of the factors of cardiovascular disease. Undeveloped nations don't have fast-food or television to watch all day, since they play outside.
D: Neutral mutation. It says the eyesight remains normal. Therefore it cannot be harmful. Changing eye color has no effect on the ability to find food. Eye color is just an appearance.