Which underlined verb is in the passive voice? the veterans gave us a lecture about the vietnam war. the lecture about the vietnam war was given by veterans. the veterans gave a lecture about the vietnam war. the veterans’ lecture addressed the vietnam war.

The lecture about the Vietnam War was given by veterans.

Explanation:

Among the options given, the only one in the Passive Voice is "The lecture about the Vietnam War was given by veterans."

In the Passive Voice, the focus of the sentence is on the action itself, not on who or what performed the action. Thus, the subject of the sentence is not the person, thing, or animal etc. who actually carried out the action. That would be the agent. The structure is:

subject + auxiliary verb (if necessary) + verb be + main verb in the past participle + agent (if necessary).

So:

The lecture about the Vietnam War - subject

was - verb be

given - main verb in the past participle

by veterans - agent