A、The white butterfly. B、The small bird. C、The bear. D、The fox. A短文中提到，某种白蝴蝶只吃卷心菜；熊吃水果和鱼；狐狸吃小动物、鸟类和水果，由此可知，答案为A)。问题中的eat only on

Many animals recognise their food because they see it. So do humans. When you see an apple or a piece of chocolate you know that these are things you can eat. You can also use other senses when you choose your food. You may like it because it smells good or because it tastes good. You may dislike some types of food because they do not look, smell or taste very nice. Different animals use different senses, to find and choose their food. A few animals depend on only one of their senses, while most animals use more than one sense.
    Although there are many different types of food, some animals spend their lives eating only one type. The giant panda eats only one particular type of bamboo. Other animals eat only one type of food even when given other choice. A kind of white butterfly will stay on the leaves of a cabbage, even though there are plenty of other vegetables in the garden. However, most animals have a more varied diet. The bear eats fruits and fish. The fox eats small animals, birds and fruits. The diet of these animals will be different depending on the season.
    Humans have a very varied diet. We often eat food because we like it and not because it is good for us. In countries such as France and Britain, people eat foods with too much sugar. This makes them overweight, which is bad for their health. Eating too much red meat and animal products, such as butter, can also be bad for the health. Choosing the right food, therefore, has become an area of study in modern life.
Questions 22 to 25 are based on the passage you have just heard.
22. What can we infer about humans and animals from the passage?
23. Which animal eats only one type of food?
24. When do certain animals change their choice of food?
25. What can we learn from the passage?