The Last Group Battle?

After Number 37 arrived, Nightingale, who was inside the pavilion, spoke coldly again. "Good. Everyone arrived within the stipulated time. Otherwise, some of you might have been eliminated! The reason we assembled all of you here today is because of an unexpected situation. We cannot go ahead with our initial plan. That is why, after the three of us instructors had a discussion, we decided to use a group battle to determine which one of you will be qualified to advance through this mission!"

"Group battle? Qualify to advance?"

Upon hearing the news, everyone seemed shocked. The current mission had only reached the second night. Based on the initial three-day time period, they still had a little more than one day left. So why was it necessary to decide things with one group battle?

"Also, advance? Advance to what? Directly obtain the qualifications to change profession into a special agent?"