Read the text below and answer the question number 23 to 25.

    Once a fisherman named Batara Guru Sahala lived in Batakland. One day, he caught a fish. To his surprise, he found that the fish could talk! It begged Sahala to set it free. Sahala did accordingly. As soon as the fish was free, it changed into a woman. She was so beautiful that the fisherman fell in love with her at once. He asked her to marry him. The woman agreed to marry Sahala. However, she told him that he must never let out the secret that she was once a fish. Sahala promised her that he would not tell anyone about it.

    They were happily married, and had two daughters. Every morning, Sahala went out fishing. His daughters would bring him his lunch. One day, however, instead of bringing the food to their father, the girls ate it. When Sahala learnt what they had done with his meal, he got very angry. He shouted at them, saying, "You behaved exactly like the daughters of a fish."

    The girls did not understand what their father meant. They went home and asked their mother about it. When they told her what he had said, she was very annoyed, Although Sahala apologized to her later, she would not forgive him for breaking his promise.

    Then, the earth began to tremble, and volcanoes started to erupt. The earth cracked to form a big hole. People said that this hole became Lake Toba.

Why did the girls' mother get angry with Sahala?