Which of the Following Is the Main Feature That Allows

Which of the following is the main feature that allows adaptation at the anatomical level to high altitudes in Bar-Headed Geese?

A) Their wingspan is above average, but the wing loading is not.
B) They do not have any anatomical adaptations, which emphasizes their physiological adaptations for oxygen transport at high altitudes.
C) Their wing loading is above average, but their wingspan is not.
D) Both their wingspan and wing loading are above average.