The correct option is A Noun
When an adjective represents a group of people or a similar entity, without being followed by a noun, then the adjective takes the place of the noun. In the sentence, the adjective 'supernatural' is not followed by noun, hence it becomes the noun, Option B is thus, correct. Option A is incorrect because an adjective modifies a noun, since there isn't any noun following the adjective 'supernatural', it isn't considered an adjective anymore and has taken the place of a noun. Option C is incorrect because verbs are words that perform an action, the word 'supernatural' is not performing any action. An adverb modifies a verb, an adjective, or another adverb. Since 'supernatural' does not modify any of these, as the sentence ends on 'supernatural', Option D is incorrect.