甲、乙、丙三位同学分别用如图所示三套实验装置及化学药品（其中碱石灰为固体氢氧化钠和生石灰的混合物）制取氨气．请你参与探究，并回答下列问题：

根据短文内容，选择正确答案
    Many people like traveling during their vacation. They go to mountains, seaside, or forests. Some people like history so they like to visit old castles  (城堡), museums and monuments  (纪念, 碑). In many foreign countries, the travel agent (旅行社) can help you plan your holiday. You can tell the travel agent what kind of holiday you like, how much money you want to spend, and the travel agent will give you a lot of information about where to go, how to get there, where to stay, and what kind of activities you can do there. One of the holidays is called "package holiday". That is, you just pay the money, and the travel agent will plan everything for you, the ticket for the train or plane, the hotel, the activities, etc.

下列关于基因突变的叙述，正确的是(　　)