The correct option is A the kind of food they eat
The function of beaks is to help the birds to access food. Birds have beaks suited for a variety of foods.
BirdType of beakPurposeParrotHookedTo crack fruits and nutsHumming birdLong and thinTo suck nectarCraneLongTo catch fishes in waterWoodpeckerLong and strongTo remove layers of bark and eat insects