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

The first-year students are bidding farewell to their seniors.

Farewell is being bid to their seniors by the first-year students.

The correct passive voice form of the given sentence "The first-year students are bidding farewell to their seniors" is Farewell is being bid to their seniors by the first-year students.

The active voice of the sentence is "The first-year students are bidding farewell to their seniors." This sentence is in the present progressive tense, which is used to describe an action that is happening now but is not finished. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the present participle of the main verb. In this case, the subject of the active sentence is "first-year students" and the main verb is "bid." The past participle of "bid" is "bid." So, the passive form of the sentence is "Farewell is being bid to their seniors by the first-year students."

The other options are incorrect because:

• Farewell is to be bid to their seniors by the first-year students." This sentence is in the future tense, which is used to describe an action that will happen in the future. However, the action of bidding farewell to seniors is happening now.
• Farewell was being bid to their seniors by the first-year students." This sentence is in the past progressive tense, which is used to describe an action that was happening now but is not finished. However, the action of bidding farewell to seniors is still happening.
• Their seniors is being bid farewell by the first-year students." This sentence is in the passive voice, but the subject of the sentence is incorrect. The subject of the sentence should be "farewell."