The sentence that is punctuated correctly is, option A. We grated one-third of that hunk of cheddar cheese. We use a hyphen for the word "one-third" because it is a compound word. A compound word consists of two or more words joined together to form a new word and meaning.
If you think about theme and understand what it is then you read the paragraph or sentence that you are reading then you will know exactly the theme of the story.
