Select the option that expresses the given sentence in passive voice.

The armed forces put up an impressive parade on Republic Day.

An impressive parade was put up by the armed forces on Republic Day.

The correct passive form of the given sentence is An impressive parade was put up by the armed forces on Republic Day.

The active voice of the sentence is The armed forces put up an impressive parade on Republic Day. This sentence is in the simple past tense, which is used to describe an action that happened in the past. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the past participle of the main verb. In this case, the subject of the active sentence is "armed forces" and the main verb is "put up." The past participle of "put up" is "put up." So, the passive form of the sentence is An impressive parade was put up by the armed forces on Republic Day.

The other options are incorrect because:

• An impressive parade have been put up by the armed forces on Republic Day. is in the present perfect tense, which is used to describe an action that has happened in the past but is still relevant to the present. The action of putting up the parade is something that happened in the past and is not relevant to the present.
• An impressive parade is putting up by the armed forces on Republic Day. is in the present progressive tense, which is used to describe an action that is happening now but is not finished. The parade was put up in the past, so the present progressive tense is not appropriate.
• An impressive parade was being put up on Republic Day by the armed forces. is also in the present progressive tense, which is not appropriate for this sentence.