听一段材料，回答下面几个小题。
How many world’s flags contain red?
A.70%.
B.80%.
C.85%.
Why do people dislike black?
A.It means danger.
B.It makes people not noticed.
C.It makes people feel afraid.
Which of the following is NOT true according to the passage?
A.Different colors have different meanings.
B. Yellow is a very relaxing color and blue is a very calm color.
C.People who wear gray want to cover themselves to all.