Me
You (plural)
Him/Her/It
Us
You (singular)
Them
I've always been told check for <em>spelling errors </em>first, which technically you are beginning the process of proofreading.
Next, I've been told to look for usage errors, which means, did you use the word in the correct context.
Then I believe you look for grammar mistakes, which includes subject verb agreements, fragments, punctuation, and can include style of the paper, which I believe looks at the sentence variety.
Hopefully this helped and good luck.
It's A. He has a heart of gold because it compares without using like or as
Maybe a visual to show what changed and how it did and maybe a text like how it did and described what changed