A、Because flying is not as common as driving. B、Because passengers on a flight are all strangers. C、Because terrorists often tak

Good morning, ladies and gentlemen. Welcome here. Today, I’d like to share with you something about security. We should know that security is two different things: it’s a feeling, and it’s a reality. And they’re different. You could feel secure even if you’re not. And you can be secure even if you don’t feel it. Really, we have two separate concepts mapped onto the same word.
    So if you look at security from economic terms, it’s a trade-off. Every time you get some security, you’re always trading off something. Now there’s often no right or wrong here. Some of us have a burglar alarm system at home, and some of us don’t. And it all depends on where we live, whether we live alone or have a family, how much cool stuff we have, how much we’re willing to accept the risk of theft.
    Now there are several biases in risk perception, a lot of good experiments in this, and you can see certain biases that come up again and again. So I’ll give you four here. First, we tend to exaggerate spectacular and rare risks and downplay common risks—so flying versus driving. Second, the unknown is perceived to be riskier than the familiar. A good example in case would be, people fear kidnapping by strangers when the data supports kidnapping by relatives is much more common. Third, personified risks are perceived to be greater than anonymous risks—so Bin Laden is scarier because he has a name. And the fourth is that people underestimate risks in situations they do control and overestimate them in situations they don’t control. So once you take up skydiving or smoking, you downplay the risks. If a risk is thrust upon you—terrorism was a good example—you’ll overplay it because you don’t feel like it’s in your control.
    So it’s important for us, those of us who design security, who look at security policy, or even look at public policy in ways that affect security. It’s not just reality; it’s feeling and reality. What’s important is that they be about the same. It’s important that if our feelings match reality, we make better security trade-offs.           
    OK, that’s all for today’s lecture. Hope you enjoy it. Thank you.
    Questions 20 to 22 are based on the recording you have just heard.
    20. What does the word "security" mean?
    21.Why do people feel flying is riskier than driving?        
    22.What should security policy designers bear in mind?