VOICE form, hence we need to CONVERT it into a passive voice form.Find the subject (He) and object (A ripe mango) of the sentence and exchange their places. The given sentence is in the simple past tense. The passive verb form for simple past is: was/were + past participle form of the verb.So, 'plucked' changes to 'was plucked'.At last line up the REMAINING part.Following these steps, we get - A ripe mango was plucked by him. If the subject isn't clear, the agent (by + Sub.) needn't be mentioned in the passive voice.Example:People FOLLOW this ritual all over the world. (active)This ritual is followed all over the world. (passive)