Answer:
Officials <u><em>at</em></u> the press conference gave little detail.
Explanation:
Prepositions are words that we use to tell the position of a noun or a pronoun in a sentence. It also tells the relation of words or elements in a sentence. Examples of prepositions are <u>"at, for, by, above, below, near, to, after"</u> etc.
The given sentence <em>"officials ... the press conference gave little detail"</em> will have the preposition "at". This is because the preposition "at" tells the location, place, or time of an event. And the officials were "at" the press conference, which is a location or a place.
So, the final sentence will be-
Officials <u><em>at</em></u> the press conference gave little detail.