Answer: b. Long necks allow giraffes to feed on higher vegetation that giraffes with shorter necks cannot reach.
Step-by-step explanation:
The natural selection is the phenomena of differential survival as well as reproduction which can be seen in the population of the same species. This is due to the fact that some organisms of the species posses better phenotypic traits over the others which helps them to survive and reproduce. These traits are passed on from parents to their offsprings.
The example of natural selection is the development of the giraffe neck. Some of the giraffe organisms developed long neck which helped them to grab leaves from tall trees in the scarcity of food at the ground level. This beneficial trait was passed on to the successive generations of giraffes.