The hack driver was recognised when the narrator returned to New Lutkins with a woman who knew the local people well. She identified the hack driver himself as Bill Magnuson, the man they had been looking for all along — Oliver Lutkins. He had been cleverly deceiving the narrator the entire previous day.
This question is from "The Hack Driver" by Sinclair Lewis. The key point examiners expect is: the narrator returned with someone who knew Lutkins personally, and she immediately recognised the hack driver as Lutkins himself. Mention the deception clearly. Note: the source passages provided are from other chapters and do not cover this story — answer is based on the prescribed textbook chapter.