Writing > Identifying Sentence Errors

The following sentence contains either a single error or no error at all. If the sentence contains an error, select the one underlined part that must be changed to make the sentence correct. If the sentence contains no error, select choice E.?

Unbelievable?as it may seem, many individuals?that fought?in the American Revolution?were still alive?in 1839,?the year?the world was introduced to photography.??No error

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