According to the context of the given sentence, the word 'charm' has been employed as a noun being followed by the determiner. Therefore, option A goes incorrect. Option C becomes incorrect as it goes out of the context of the sentence. Thus, only option B corresponds by functioning as a noun and accomplishes the meaning of the sentence and the sentence would imply 'Morton had enough attractiveness/appeal/charisma(charm) that he could win even the coldest of hearts with his smile'. Therefore, <u>option B</u> is the correct answer.
In the sentence, the word charm is used as a noun to describe one of Morton’s qualities. This word should be replaced with another noun. So, the verb forms can be eliminated. Also since charm is used to mean one of Morton’s qualities, some of the noun forms can also be eliminated. The noun forms ornament and fascination cannot be correct because they are not qualities. Thus, the noun appeal, which is also a quality, best replaces the word charm in the sentence.
