(A) unmanageable

　　(B) uNPRedictable

　　(C) understandable

　　(D) unreliable

　　30. According to the passage, what is the purpose of examining a sample of a population?

　　(A) To compare different groups

　　(B) To predict characteristics of the entire population

　　(C) To detect differences not observable in the whole population

　　(D) To compile more accurate data