Final answer:
Montag is fearful of the Hound at the firehouse because it may lead to the discovery of his book collection.
Step-by-step explanation:
Montag is fearful of the Hound during their interaction at the firehouse mainly because it may lead to the discovery of his book collection. The Hound is a robotic device used by the firemen to track down and eliminate individuals who possess books. Montag has been secretly collecting books, which is illegal in the dystopian society portrayed in the novel 'Fahrenheit 451' by Ray Bradbury. If the Hound were to detect the presence of books, Montag's secret collection would be exposed, resulting in severe consequences for him.
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