Which of the following best explains why the beak shape of each species of bird

Which of the following best explains why the beak shape of each species of bird.

Which of the following best explains why the beak shape of each species of bird develops differently?

A.	each beak shape helps the birds to produce different songs

B.	each beak shape is an adaptation to a specific source of food

C.	each beak shape help protect the birds from each other