A、China. B、Egypt. C、Spain. D、Siberia. D讲座中提到，大蒜源于西伯利亚的沙漠地区，因此答案为D)。

Moderator:
    Good evening, ladies and gentlemen. It’s my honor to introduce our speaker for today’s lecture, Dr. Roger Coffin. Dr. Coffin, a nutritionist and researcher in food, has written many articles on food science, which is more and more important in society nowadays—even has a profound impact on our daily lives. Welcome, Dr. Coffin.
    Dr. Coffin:
    Good evening, everyone. Today we are going to look at a food stuff: garlic. We will explore a little of its history and examine some of the many different ways it’s been used over time.
    All around the world, for over 4,000 years, garlic has played many important roles in our daily lives. Many countries grow garlic today, like China, Egypt, Spain, etc. Garlic originates from the desert region of Siberia, where the summers are dry and hot. In order to survive, the wild garlic plant had to adapt to this harsh climate. Garlic had to grow when there was moisture, in the spring and fall, and it also had to be able to survive without water for the exceptionally dry summer and winter months. Garlic adapted to its environment so that the growing cycle began in the fall, to take advantage of the available moisture. When the cold winters or the hot dry summers arrived, it became inactive. When the spring rains arrived, the plant could continue on its growth process. A healthy root system and relatively small leaves is the key to the survival of the plant. These traits make garlic a very healthy plant, capable of growing in poor soil in harsh climates with little or no care. Once discovered by humans, it is no wonder that garlic quickly became an important crop of almost every civilization in the world.
    An Egyptian manuscript from 1,500 BC recommended garlic for 22 diseases. The Egyptians fed it to slaves building the pyramids to increase their toughness. Garlic was so valuable to the Egyptians that 15 pounds of garlic would purchase a healthy male slave. In ancient Greece and Rome, garlic was claimed to have more uses—everything from repelling scorpions to treating dog bites. In the Middle Ages, soldiers returning to Europe after faraway battles were generally credited with bringing garlic back with them, for it was thought to prevent the plague. Garlic was so prized in ceremony and ritual, and it’s said that lambs offered for sacrifice in China were seasoned with garlic to make them more pleasing to the gods.
    OK. That’s all for today’s talk. Hope you all like it. Thank you!
    Questions 16 to 19 are based on the recording you have just heard.
    16.What does the introduction part say about food science?
    17.Where does garlic originally come from?
    18.When does garlic begin its growth cycle?
    19.What could garlic do according to Europeans in the Middle Ages?