Correct Answer: A hostile hunter killed the tiger on an unfortunate day.

Solution : The correct choice is the f ourth option.

Active voice is the voice where the subject performs the action. When converting a sentence from the passive voice to the active voice, the subject performs the action rather than the action received by the subject.

The structure of the active sentence in the case of the simple past tense is: " Singular subject + past form of the verb + object + time phrase."

Therefore, the active voice sentence is: A hostile hunter killed the tiger on an unfortunate day.