Questions 17～20 are based on the following report about human height. You now have 20 seconds to read Questions 17～20. Which of the following plays a key role in body growth according to the passage

A. She is thirsty for promotion.
B. She is tired of her present work.
C. She wants a much higher salary.
D. She wants to save travel expenses.

A. 5.

B. 24.
C. 17,000.

D. 9,000.