Does having a "C" on your high school transcript negate your chance?
Every negative on your record is a good reason for a top tier school to choose someone without those negatives instead of you. What you should ask yourself is whether you have some overriding reasons why they should choose you over them. Unless youve win the Intel Science Prize, or youre a top quarterback prospect, the alternative will be to instead choose a school that better matches your actual record instead of just lusting after schools that are out of reach.