Three blondes   were being trained to become detectives by a policeman. To test their skills in recognizing a suspect  , the policeman showed the first blonde a picture for five seconds and then asked how she could recognize him. She thought it easy, for the suspect had only one eye. The policeman felt disappointed at this funny answer. He showed the second lady the picture for five seconds and asked her how she would recognize him. The second blonde giggled, flipped her hair, and said, "Ha! It's easy to find the one-eared person!" Her answer also made the policeman angry. Turning to the third lady, he asked, "This is your suspect, and how would you recognize him?" He added quickly, "Think hard before giving a stupid answer." The third blonde looked at the picture carefully for a moment and said, "HMMMM ... the suspect is wearing contact lenses  ." The policeman was surprised and speechless, because he really didn't know himself if the suspect wore contacts or not. "Well, that is a good answer. Wait here for a few minutes while I check his file." He left the room and went to his office, checked the suspect's file in his computer and returned with a beaming smile. "Wow! I can't believe it ... it's TRUE! The suspect does in fact wear contact lenses. Good work! How were you able to make such a wise observation?" "That's easy," the blonde replied, "he can't wear glasses because he only has one eye and one ear!" Which of the following cannot conclude from the passage that detectives should have?
They must be charming. Their observation must be keen. They must be humorous. They must be good at thinking.