Final answer:
The redundant phrase in the sentence about Helen Keller is 'an autobiography about her life.' Removing 'about her life' results in a clear and concise sentence without losing meaning.
Step-by-step explanation:
The redundant phrase that can be removed without changing the meaning of the text “When Helen Keller was twenty-two years old and still a student at Radcliffe College, she began writing an autobiography about her life” is “an autobiography about her life”. The word autobiography inherently means a book about one's own life, so specifying “about her life” is unnecessary and redundant. This sentence can be revised to “When Helen Keller was twenty-two years old and still a student at Radcliffe College, she began writing her autobiography.” This revision maintains the original meaning without the redundant phrase.