Read the text carefully!

THE LEGEND OF TOBA LAKE

(Source: http://www.kursusmudahbahasainggris.com/2016/10/folk-tales-dongeng-bahasa-inggris-sd.html)

    Once upon a time, there was a handsome man. His name was Batara Guru Sahala. One day, he caught a fish. He was surprised to find that the fish could talk. It begged Sahala to set it free.

    As soon as the fish was free, it changed into a woman. She said that he had to keep the secret that she was once a fish. Sahala promised that he would not tell anyone about it.

    They were married happily and had two daughters. One day, Sahala got very angry to his daughters and said that they like the daughters of a fish. The children went home and told their mother about it. Their mother was annoyed, because Sahala broke his promise.

    Then the earth began to shake and volcanoes started to erupt. The earth formed a big hole. People believed that the hole became a lake. Then this lake is Lake Toba.

How many children did Sahala have?