Select the correct passive form of the given sentence.
Are liberals and populists just searching for a new master?

Correct option is D

The correct passive voice is (d).
Explanation:
Active: Are liberals and populists searching for a new master?
Passive: Is a new master being searched for by liberals and populists?
Structure:
Active: Subject + are + verb-ing + object.
Passive: Object + is/are + being + past participle + by + subject.