Indian Navy Entrance Test Model Paper 1

The correct solution is option 1.
When changing from active to passive voice, the object of the active sentence becomes the subject of the passive sentence and the subject of the active sentence becomes the object of the passive sentence (or is dropped).
We follow the order ”Subject + helping verb+ past participle+ by+ agent.
Here the verb is ‘tighten’ whose past participle is ‘tightened’.
So, the correct answer is, “The workers are to be tightened by organisations.”