Question

in a population of giraffes, some have slightly longer necks than others. if the main food source becomes leaves on taller trees, what would be the most likely result for the population over time?
the giraffes would all learn to stretch their necks longer in their lifetime.
the trait for short necks would become more common in the population.
the population of giraffes would immediately stop evolving.
the trait for long necks would become more common in the population.

Explanation:

The problem is about giraffe evolution based on food source (leaves on taller trees). According to natural selection, giraffes with longer necks can reach the leaves better, survive and reproduce more. So the trait for long necks would become more common. The fourth option (from top) says "The trait for long necks would become more common in the population" which matches this concept. Other options are incorrect: stretching necks doesn't change genetics (first), short necks would be less common (second), evolution doesn't stop (third).

Answer:

The fourth blue box (from the top) with the text "The trait for long necks would become more common in the population."