Correct Answer: Lights were switched off by them in memory of the martyrs.

Solution : The correct choice is the first option.

Explanation: The passive voice is a grammatical construction where the subject of the sentence receives the action rather than performing it. In the passive voice, the object of the active sentence ("lights" in this case) becomes the subject of the passive sentence. The verb is changed to its past participle form ("were switched off"), and the original subject ("they" in this case) is introduced with the preposition "by".

The passive voice sentence in the case of the simple past tense follows the structure: "Plural object + were + past participle of the main verb + by followed by the agent of the action."

Therefore, the correct answer is: Lights were switched off by them in memory of the martyrs.