Some giraffes have long necks and some have shorter necks. The ones with longer necks can reach food sources like tall trees as well as eat grasses on the ground. How will this difference MOST LIKELY help the giraffe population?
A) Their number will remain unchanged.
B) Over time, more will have longer necks.
C) Giraffes will move from place to place for food.
D) There will be great differences among the giraffe population.

Among the two types of giraffes, the ones with longer necks have an advantage of obtaining food from tall trees as well as the grasses on the ground.
Due to this advantage, the tall necked giraffes are much better adapted to survive in case of calamities involving food shortage as they can obtain food from varied source.
Thus, the trait of the long neck will be selected by natural selection and the population of long neck giraffe will increase.