<p>Personally, i wouldn't mention the C's. Yea, may be able to put across a very convincing reason for why you got them, but many people have probably tried this. </p>
<p>Your personal statement gives you very little space for a lot to say, use that space more wisely and talk about something personal and meaningful to you, showing that you are unique. That would be better than just arguing over your grade.</p>