Change in passive: ‘I wrote a letter’

C. A letter was written by me.

Here’s a breakdown of the rule you used to convert the sentence to passive voice:

Active Voice Structure: Subject + Verb + Object

Passive Voice Structure: Object of Active Voice Sentence + Verb (to be + past participle) + By + Agent (Subject of Active Voice Sentence) (Optional)

Following this rule:

• Object of Active Voice Sentence: “A letter” becomes the subject in the passive voice sentence.
• Verb: “Wrote” becomes the past participle “written.” The verb “to be” (was) is added before “written” to indicate the passive voice.
• By + Agent: “By me” clarifies who performed the action (optional, but included here).