A

    In the old times, there was a king. He had a very beautiful garden. In the garden, there was a tree with golden apples on it. But one day, one of the apples was missing. The king decided to order a person to keep watching the tree at night.
    The king had three sons. He decided to send the eldest one to watch the tree. But in the middle of the night, the eldest son fell asleep. The next morning, another apple was missing.
    The second night, the king sent the second eldest son. But the second eldest son also fell asleep at midnight. And another apple was missing the next morning.
    The third night, the king sent his youngest son. The youngest son kept watching the tree and ordered himself not to sleep. At twelve o'clock, he saw a bird. It was a golden bird. It picked an apple and flew away, but it left a golden feather(羽毛). The youngest son picked it up, and the next morning, he took it to the king. He told his father what he had seen at night. Hearing this, the king was very happy. He ordered his youngest son to guard(看守) the tree every night. He wanted him to catch the bird. However, in the end, they couldn't catch the bird and all the golden apples on the tree were taken away by the golden bird.