Correct Answer: Instructions on how to use the gadget are given by this brochure.

Solution : The third option is the correct answer.

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 sentence becomes the subject in the passive voice.

The structure of the passive sentence in case of the simple present is: "Object + are + past participle of the main verb + by + agent of action."

Therefore, the correct answer is: "Instructions on how to use the gadget are given by this brochure."