The largest bird is:

Students of class $XII$ were given a list of the following characters: clawed toes,curved beak,feathers,pneumatic bones,wings,and fur. In this list,how many are volant adaptations?

What type of eggs do birds have?

Which one of the following organisms bears hollow and pneumatic long bones?

$S$ - Statement: In ostriches,the aortic arch turns to the left.
$R$ - Reason: In kangaroos,the aortic arch turns to the right.

Give scientific reason: Birds show adaptations for flight.