Choose the grammatically correct sentence.

The correct answer is Option (1) → I had reached the school before the peon rang the bell.

Past perfect with simple past:

• When two actions happened in the past, one after the other:
  • the earlier action takes the past perfect (had + past participle);
  • the later action takes the simple past.
• Before introduces the later action.
• This sentence: reaching school came first (had reached); the bell came later (rang).
  Example: The train had left before we reached the station.

Why the Other Options are Incorrect?

Option 2: I reached the school before the peon ring the bell. — Incorrect. "ring" is the base form; a past action needs "rang", and the singular subject "the peon" could not take "ring" even in the present.

Option 3: I had reached the school before the peon rings the bell. — Incorrect. "rings" (present) does not match "had reached" (past); both actions are in the past.

Option 4: I have reached the school before the peon ring the bell. — Incorrect.

• "have reached" (present perfect) does not suit a completed past sequence.
• "ring" should be "rang".