It should be 3! That is the only logical answer to the question...
Soaring and gliding birds like eagle, vulture, albatross, sea gulls etc are efficiently adapted to utilize the air currents in their flight.
Explanation:
The soaring flight and gliding movements are special adaptation developed by birds to meet the challenge of increasing turbulent air current.
Birds have the extraordinary skill of flying smoothly and effortlessly even at very high altitudes
Birds soar by using thermal and dynamic soaring techniques.
Gliding movements help the birds to deflect the wind downward which helps to lift their bodies in the air. They do not flap their wings during gliding but just dive straight into the air which helps to increase their speed.
The adaptation of the bird’s structure with very light but strong bones on their wings helps to soar and glide in the air.
" As we follow along on a cladogram, it will split at nodes into two or more internodes a specitation event (the formation of new species). The line between two specification events, the internode, represents at least one hypothetical ancestor."
