Question 23 to 26 are based on the following news. At the end of the news item, you will be given 20 seconds to answer the questions. Now listen to the passage. About ______ blacks have been killed in the past three years.

A. Their tasty meat.
B. The principle of their defense system against disease.
G. Their solid skin.
D. The principle of their birth modes.

A．Bone structure.
B．Smell ability.
C．Birth mode.
D．Recover ability against disease.