Features of birds are- I: Their body shapes II: Smooth waxy feathers III: Hollow bones IV: Beaks Which are flight adaptations?

Features of birds are- I: Their body shapes II: Smooth waxy

1.	Features of birds are- I: Their body shapes II: Smooth waxy feathers III: Hollow bones IV: Beaks Which are flight adaptations?
A.	Only I and II
B.	Only III and IV
C.	Only I, II and III
D.	I, II, III and IV
Answer» D. I, II, III and IV