Select the correct Passive form of the given sentence.

My helper had cleared a spot under a walnut tree.

A spot under a walnut tree had been cleared by my helper:

Here's why:

• The original sentence is in the past perfect tense ("had cleared"), indicating an action completed before another past action.
• The passive voice is formed by using the past participle of the verb ("cleared") preceded by the auxiliary verb "had been."
• The subject of the original sentence ("my helper") becomes the agent of the passive voice, introduced by the preposition "by."

Therefore, "A spot under a walnut tree had been cleared by my helper" accurately conveys the original meaning in the passive voice.