Correct Answer: Our country witnessed a terrible disaster.

Solution : The correct choice is the third option.

Active voice emphasises the doer of the action, while passive voice emphasises the receiver. To convert passive to active, we make the subject perform the action and rephrase the verb.

The structure of the active voice in the case of the simple past tense is: Subject + past form of the verb + object.

Therefore, the correct sentence would be: "Our country witnessed a terrible disaster."