Correct Answer: The site for our new factory has been finalised by us.

Solution : The correct choice is the third option.

Passive voice is the voice in which the object experiences an action rather than the person who performs the action. Hence, the object in the active voice becomes the subject in the passive voice.  The conversion to passive voice shifts the focus from we (the doer of the action) to the site for our new factory (the receiver of the action).

The structure of the passive sentence in the present perfect tense is object + has + been + past participle form of the main verb + by + agent of the action .

Therefore, the sentence in the passive voice is: The site for our new factory has been finalised by us.