In "Avatar: The Last Airbender", which element does Aang begin to learn after being defrosted?

In Avatar: The Last Airbender, Aang begins to learn waterbending after being defrosted because he is initially found by Katara, a skilled waterbender from the Southern Water Tribe. Katara becomes Aang's waterbending teacher and helps him harness his abilities in manipulating water. As the Avatar, Aang must master all four elements, and water is the first element he focuses on due to his circumstances and the guidance he receives from Katara.