Answer:
Adverb
Explanation:
The word today can function as a noun, an adjective or an adverb, depending on the context. As an adverb, this word means on this present day, at the present time or in these days, and it modifies a verb by providing information about when something happens. In the sentence, today is an adverb because it modifies or gives further detail of the verb opened and provides information of when the cafeteria was opened.
On the other hand, when today acts as a noun, it means: this present day (E.g.: Today is sunny), and when it is used as an adjective, it means of the present era or up-to-date and it modifies a noun (E.g Her today look is stunning).
