Answer:
Correct option is B)
Option B 'adverb' is the correct answer as 'clearly' is modifying the meaning of the verb 'reads'; simply put, it shows how Bill read the story.
Option A is an incorrect answer because a 'pronoun' belongs to that category of nouns that can be used as a substitute for nouns. 'Clearly' does not substitute any given nouns.
Option C is incorrect because an 'adjective' is any word naming an attribute of any noun and the underlined word is not regarding nouns. 'Clearly' means someone is ready and prepared and there are no obstacles, it is modifying the verb 'reads'.
Option D is incorrect because a noun is a naming word and 'clearly' is not a name of anything; it is an action word.