Identify the sentence written in passive voice:

The correct answer is Option (3) → you are requested to complete the project

Passive voice:

• In the passive, the subject receives the action instead of doing it.
• Form: a form of "be" + past participle (is written, was taken, are requested).
• This sentence: are requested = "are" + past participle "requested". "You" are the ones to whom the request is made, and the doer is not named. Its active form would be "We request you to complete the project."
  Example: Visitors are requested not to touch the paintings.

Why the Other Options are Incorrect?

Option 1: someone stole my watch — Incorrect. The subject someone does the action "stole": active voice. (Passive: My watch was stolen.)

Option 2: we expected him to call — Incorrect. The subject we does the action "expected": active voice.

Option 4: you must deliver this passage — Incorrect. "must deliver" is modal + base verb with "you" as the doer: active voice. (Passive: This passage must be delivered.)