Choose the correct passive voice: "The city had installed new traffic signals before the accident rate dropped."
- A. New traffic signals have been installed by the city before the accident rate dropped.
- B. New traffic signals had been installed by the city before the accident rate dropped. ✓
- C. New traffic signals had being installed by the city before the accident rate dropped.
- D. New traffic signals were installed by the city before the accident rate dropped.
Correct answer
B. New traffic signals had been installed by the city before the accident rate dropped.
Explanation
Past perfect active becomes past perfect passive: 'had been installed'.