Usually the reason is D. It can make us biased, I don't see any other option making sense
Mary Brown's dog symbolizes the child in a way the police can get away with the killing even if the child or citizens are innocent.
The police showing no remorse about killing an innocent life of the dog/child demonstrates the corruption of the environment there.
When you switch the sentence around such that the subject is being acted upon.
Here's what a sentence with active voice would look like:
John kicked the ball.
In this sentence, John is the subject, and he's kicking a ball. The subject is acting upon an object.
Now, what would happen if we made the ball the subject instead?
The ball was kicked by John.
This is passive voice. The ball is the subject, and it was acted upon by an object, in this case John.
What sets off appositives in the sentence is the use of the quotation mark, comma (,). This indicates that the phrase is just an added information in the sentence, and if omitted will never change the whole thought or idea of the sentence. Aside from commas, parentheses or dashes can be used as well.
