First Certificate in English (FCE) 2 Practice Test

The key idea is how we express timing with prepositions for moments. The natural way to say the initial moment is “at first,” a fixed expression meaning initially or in the beginning. So the sentence fits perfectly: it sets the scene from the very start, before anything else happens.

Other options don’t work as a natural time expression with “first.” “In first” isn’t a standard collocation for marking a moment in time, and “on first” isn’t used to indicate the initial stage here. “Before” would require a different structure to express what comes earlier, not a simple preposition before the word “first.”