Answer:
The letter was written yesterday.
Step-by-step explanation:
Yesterday is a keyword that indicates the action happened and ended. Therefore, we have to use past simple tense.
That leaves us with wrote and was written choice. Last two choices are past perfect and they should only be applied when there consists of past tense in one clause —> e.g I had eaten rice before I went to bed.
Next, we have to understand between active voice and passive voice.
Active Voice
Subject + Verb + Object
An example of active voice is:
- I eat rice.
- I write a book.
- I hit a desk.
On the other hand, we have:
Passive Voice
Object + verb to be/have + been (if there is) + past participle + by subject (if there is)
An example is:
- Rice is eaten by me.
- A book is written by me.
- A desk is hit by me.
Active voice starts with subject causing something to object.
Passive voice starts with object being caused something by subject.
And we know that a letter cannot write itself so it cannot be a subject but an object.
Hence, the letter was written yesterday is correct, indicating that the letter was being done and not letter doing.