请根据下面的短文回答66-70题 Anne Sullivan could not

问题：

请根据下面的短文回答66-70题
Anne Sullivan could not teach Helen Keller to speak until some other important things had been learned. The little girl had to learn to control her actions and feelings. She had to learn that she could not always do what she wished to do. She had always been able to get what she wanted by using force. The teacher bad to change such habits without breaking the child’s spirit.
Miss Sullivan’s battle began Sometimes, there was real fighting between the wild child and the p young teacher. At last, however, the battle was won by Miss Sullivan, who had succeeded in showing Helen that she loved her and wanted to help her. The child and her teacher became friends. They continued to be friends until the teacher’s death fifty years later.
The day on which Helen finally accepted Miss Sullivan as her friend and teacher was a great day in Helen’s life. After that, the teacher could begin to teach the child language.

How long did their friendship go on
[A] Five years. [B] Fifty years.[C] Sixty years.