Answer:
The boxer Mohammad Ali remarked, "The man who views the world at fifty the same as he did at twenty has wasted thirty years if his life."
Step-by-step explanation:
The correct quotation is the use of the correct punctuation as well as the other elements of a quoted text. This means that when quoting words or sentences said by another person, the correct form of doing it will include punctuation, the words, the attribution, etc.
Now, attribution, in this sense, is the act of regarding or admitting/accepting something that's done by someone. In the given sentence, the quote is attributed to the boxer, Mohammad Ali. So, the attribution will refer to him.
Thus, the correct quotation after putting the attribution at the beginning is-
The boxer Mohammad Ali remarked, "The man who views the world at fifty the same as he did at twenty has wasted thirty years of his life."