Given a question and its paraphrases, answer the question. The answer should exactly answer all the questions given without any ambiguity. Don't give partial answers.
Q: Questions: ['what helen keller sister name?', 'what was hellen kellers little sisters name?', "what is the name of helen keller's little sister?", 'what was the name of helen kellers little sister?', "what was hellen keller's little sister's name?", 'what was helen kellers little sister name?']
A:
mildred keller