Long beak with saw-like edges is an adaptation in

A long beak with saw-like edges (also described as having tooth-like serrations or denticles) is a specific adaptation found in pelicans. This feature serves several vital functions such as grip, water drainage (the "saw-like" structures allow the bird to drain excess water from its beak while keeping the prey trapped inside before swallowing), tearing prey(in some species, these structures act like sharp shears to help tear through tougher prey). 

A. wood pecker: Woodpeckers have strong, chisel-shaped beaks adapted for drilling into wood and excavating insects. They do not have saw-like edges.

B. kingfisher: Kingfishers possess long, straight, dagger-like beaks. This shape is streamlined to allow them to dive into water with minimal splash and resistance, but the edges are not saw-like.

D. duck: Most ducks have broad, flat beaks with comb-like structures called lamellae for filtering food from water. While some specialized ducks like mergansers are nicknamed "sawbills" because of their serrated beaks, the term "saw-like edges" in standard biological questions of this type most frequently refers to the pelican's adaptation for managing large quantities of water and slippery fish.