the crew members _______________ beneath the ship for a number of hours when their oxigen ran out.

1. has been trapped
2. was trapped
3. had been trapped

빈칸에 세 가지 중에 하나가 들어가는데 어느건지 잘 모르겠네요 ㅠ.ㅠ 설명 해주시면 감사하겠습니다!