阅读短文，选择正确答案，回答下面的问题。

    Hello, I'm Mr Jason. Welcome to my farm. Look! These are white sheep. They are cute. I have twenty sheep. Look at those animals over there. They're horses. They can run fast. There are fifteen horses on my farm. Can you see four cows under the trees? They're big. Look! Those are hens and ducks. They are on the grass. I have a lot of hens and ducks.