A、Why Jack needs glasses. B、Research Jack has done for his economics paper. C、The disadvantages of working in an office. D、How u

W: Hi, Jack. How is your economics paper going?
M: It’s coming along. But I’ve been staring at this computer screen for hours and my eyes hurt.
W: Yeah. Doing that can make your eyes really dry and tired. You should take a break.
M: I can’t. I have to get this paper written. It’s due tomorrow.
W: You know I read about computers and eye problems recently. The article says that they are usually caused by not blinking your eyes enough.
M: Blinking? I thought I just needed new glasses.
W: No. When you blink, the movement of closing and opening your eyes, even though it happens really fast, helps moisten your eyes. It’s the lack of moisture that causes the problem.
M: That makes sense. But what does it have to do with the computer?
W: People who use computers tend to stare at the monitor and blink less often than they normally would. That leads to dry, irritated eyes.
M: Well, that’s certainly how mine feel now. They really hurt.
W: The article I read about the office workers found that the workers averaged 22 blinks a minute when relaxed. But just 7 a minute while looking at the text on a computer screen.
M: Wow. That’s quite a difference.
W: They also kept their eyes open wider which means the moisture evaporated more quickly.
M: I wonder if using some kind of eye-drops will make them feel better.
W: That might help. But the best prescription is to take a break and rest your eyes.
M: OK. Let’s go get some coffee. I can finish this later tonight.
27. What are the speakers mainly discussing?
28. Why is blinking important?
29. What should Jack do to improve his situation?
30. What can be inferred about Jack?