Correct option is B
Option (b) "quite fastly" contains the error. The word "fastly" is incorrect because "fast" is both an adjective and an adverb, so it should be used as "quite fast" instead of "quite fastly."
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Grammatical rule used: When describing the manner in which something is done, "fast" is used as an adverb without needing the "-ly" suffix.
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Example: The car drove quite fast along the highway.