Those investors who sold stocks just before the stock market crash in 1929 were either wise or exceptional (Option D) lucky.
Sentence correction or sentence improvement is a type of grammatical practice where a sentence is given with a word or a phrase that requires grammatical changes or improvement.
Now,
Hence, Option D is the answer and the part of the sentence that needs correction; correction would be: "exceptionally lucky."
To learn more about sentence correction, refer to the link: https://brainly.com/question/14632568
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