Which of the following statements are correct?
(A) Hollow bones in birds helps them to fly.
(B) Streamlined body of birds helps them to walk on ground.
(C) Perching birds have three toes in front and one at the back.
A (A) and (B) only
B (B) and (C)only
C (A) and (C) only
D (A), (B) and (C)