admission getting rescinded?

<p>I have just received a letter from Columbia saying my senior year grades are not on par with the ones from my previous years.They want an explanation. I was accepted early decision and slacked off, ending up with straight Bs and a C. I honestly have nothing to blame on but myself- my parents didn't die and i don't suffer from some life-threatening illness. Any advices on how I should address this? Am I ending up collegeless...?</p>

<p>What happened in the end?</p>