Answer:
B). Charm, n. attraction, appeal, charisma.
Step-by-step explanation:
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, option B is the correct answer.