Option A - A preposition is a word that is used before a noun, a noun phrase, or a pronoun, connecting it to another word. For example, 'A cat is sitting on the table.' 'On' is a preposition used before the noun 'the table' to explain the position of the cat. 'Aftereffects' is not used before or after a noun. Thus option A is incorrect.
Option C - 'Adjective' is a word that describes the noun. For example, 'She is beautiful'. As 'aftereffects' doesn't describe the noun 'drug', it is not an adjective. Thus option C is incorrect.
Option D - 'Adverb' is a word that describes a verb, an adjective or another adverb. For example, 'She cooks nicely.' 'Nicely' explains how she cooks. As 'aftereffects' doesn't explain any action here, it is not an adverb. Thus option D is incorrect.
Option B - A noun is a naming word. For example, 'Creation is an art'. 'Creation' is the name of a concept of creating. As 'aftereffects' is the name given to a concept, it is a noun. Also, 'effects' is a noun too. Thus option B is the correct answer.