1. Why do birds sing?
A. Birds sings to find a mate.
B. Birds sings to locate one another.
C. Birds sings to warn another bird.
D. All of the above.

2. How can we determine the complexity of the song?
A. by how long it is
B. by how loud it is
C. by how complicated it is
D. by its instinctiveness

3. Which word is the opposite of complexity?
A.Simplicity
B. trouble
C. problem
D. intricate

4. How can we determine the health of a bird?
A. by the length of its song
B. by the intensity of its song
C. by the complexity of its song
D. By the pitch and loudness of its song

5. How young bird perfect its song?
A. by natural instinct
B. by listening and interaction
C. by practice
D.by vocalizations ​