A、A type of coffee bean. B、An artificial flavoring. C、An alkaloid stimulant. D、A kind of prescription drug. C根据句(3一1)可知，女士把咖啡因理解

W: Welcome to our Sunday TV program Enjoy Food & Drinks. Today, we are glad to have invited Professor David from Kansas University as our honored guest. Professor David is an expert in coffee. He has been studying coffee for more than 20 years.
M: Good morning. Do you drink coffee, Cathy?
W: Sure! Every day!
M: So do I. According to some statistics, about 8 of every 10 Americans drink coffee each morning, and the typical American will have three cups of it per day. But it isn’t just Americans who need their daily caffeine fix. (1) More than a third of all the people in the world drink coffee, which makes it the number-one processed beverage on the planet.
W: (2-1) Most people drink coffee for the stimulation provided by caffeine. Am I right?
M: (2-2) Definitely! But do you happen to know what caffeine is?
W: Er... (3-1) It’s a kind of drug, isn’t it? Like nicotine?
M: (3-2) You can say that again. It’s a mild natural stimulant, a type of alkaloid. Like most drugs, it’s beneficial in small amounts. It’s been shown to help improve coordination and increase concentration. W: I see. But will it bring us any harm if we drink it every day?
M: Like most drugs, it’s harmful in large amounts, and several studies suggest it could contribute to serious illnesses such as cancer and heart disease. Would you drink coffee because of the taste alone? I guess probably not. (4) One cup contains about 100 milligrams of caffeine, which is twice as much as a cup of tea and three times as much as a cup of cola.
W: How large is a cup by the way?
M: Good question. Um, normally six ounces. Now, because of its popularity, coffee has become one of the world’s most important commodities. For example, between 1998 and 2000, a total of 6.7 million tons of coffee was produced each year, and experts forecast that production will rise above 7 million tons annually by 2020.
W: Wow! That makes coffee one of the most valuable products in terms of its large consumption.
M: Indeed! Coffee is the world’s fifth, no, make that sixth largest agricultural export in terms of value. Though people in Europe and the United States drink 85% of all exported coffee, it is becoming increasingly popular in traditional tea-drinking Asian cultures such as China and Japan. (5) Japan, in fact, has become the world’s, let’s see, seventh largest retail market for coffee, as well as its third largest importer.
W: And I have heard that Starbucks has been reaping huge profits from the Chinese market.
M: You are absolutely right! And in China, Starbucks has opened almost 450 shops since first entering the country in 1998. So, coffee clearly plays an important role on today’s world stage.
This is the end of Part One of the interview. Questions 1 to 5 are based on what you have just heard.
1. How many people all over the world drink coffee?
2. Why do most people drink coffee?
3. What is caffeine?
4. Which of the following statements about coffee is TRUE?
5. Which country has become the world’s third largest importer of coffee?