The use of parenthesis is to include something in a sentence that isn't necessary to the sentence. Meaning, if taken out, the sentence would still make sense.
So, for each sentence, take out what is in parenthesis and see of the sentence still makes sense.
A. The cowboy hat it skiing fit perfectly.
- This does not make sense, so it is incorrect
B. I planned to wear it skiing fit perfectly.
- Though this ALMOST makes sense, it is missing the main subject, which is the cowboy hat
C. The cowboy hat fit perfectly.
- Makes sense!!
D. The cowboy hat I planned to wear it skiing.
- This is missing the main verb. So, now the sentence is incomplete.
The answer is C :)
