Read the text carefully and answer the questions! (Bacalah text dengan cermat dan jawab pertanyaannya!)

    A long time ago, there was a poor farmer. He lived in a small bamboo hut near his rice field.

    One day, he wanted to catch some fish for his dinner. Just he caught a big and fresh fish, he heard a voice. "Please don't kill me. If you let me alive and put me into your rice field, you will have your dinner on your dining table". "No problem", said the farmer.

    When the farmer went home, he was surprised. His dinner was already set on the table. Another day, he went to the rice field and looked for the fish. He heard some voice, "I am here, near you.” Suddenly there was a beautiful girl beside him. "Are you the fish that I caught yesterday?" "Yes, I am. Thanks for your help. Would you marry me?" replied the girl. "Of course, I would." said the farmer happily. "But on one condition. Never tell our children that I was once a fish", added the girl.

    Well . . . after one year, they got a son. They called Sam. Years later, the mother asked Sam to bring lunch to his father at the rice field. Feeling hungry, the boy ate his father's lunch on the way. Knowing this, the farmer was angry. "You are a naughty boy! You will not be a good boy because you are actually a son of fish!" The boy cried and told his mother what he heard from his father. The mother went to the rice field and said angrily, "You have broken your promise. Now you must be punished." Then, she left her husband. And suddenly a big tide came and engulfed the village. The flood made a deep large lake. People call it Lake Toba.

What is the communicative purpose of the text?