The Dragon Boat Festival is an interesting Chinese festival. Usually, it's in May or June. People all like it very much.

    They usually have dragon boat races. Dragon boats are very long. They look like dragons. In every boat, there are many people rowing boats. Dragon boat races are very interesting for Chinese people.

    At the Dragon Boat Festival, people also eat zongzi. People usually use rice, meat(肉), vegetables and other things to make zongzi. There are many kinds of zongzi. They are all nice, and people usually give them to their friends.

    The Dragon Boat Festival is a great time for people.

根据短文内容，回答下列问题。

医生从小王消化道的某器官里取出少量的液体，经化验发现含有葡萄糖、麦芽糖、淀粉、氨基酸、脂肪、维生素等物质，该器官是（　　）