The beak of a hummingbird is long, curved, and tubular, which is specifically adapted for feeding on nectar from flowers. The hummingbird's beak allows it to reach into flowers with a long, slender shape that suits its diet. This tubular structure helps the bird extract nectar efficiently without disturbing the flower too much. Other birds, such as those with conical beaks, are adapted for different feeding habits, such as cracking seeds. Thus, the correct answer is option (B).