阅读短文，然后根据其内容从A、B、C、D中选出最佳选项。

Mr Li: Sam, did you enjoy your first Spring Festival in China?

Sam: Yes, I did. During this festival, many family members get together.

Mr Li: Yes. I hear that at Thanksgiving Americans also get together for a special meal. It sounds similar.

Sam: Yes. It's similar. During these holidays, both the Chinese and Americans come home and have a big dinner. It's great fun.

Mr Li: What do you think are the main differences between the Spring Festival and Thanksgiving?

Sam: Well, we take part in different activities and eat different kinds of food. In China, people usually set off fireworks and eat dumplings. In the US, we usually watch a Thanksgiving parade and an American football game on TV. We also eat turkey.

Mr Li: That's interesting.

世界上最大的经济体的货币是（　   ）