<p>December 4 2008...</p>
<p>Why is it C not D?</p>
<p>Is it because D should have "An African American writer.." not just "African American writer..."?</p>
<p>Thanks!</p>
<p>D sounds as if the person saying it is addressing the person to whom he's speaking as "African American writer", and that he's letting him know about Rita Dove. It just sounds weird.</p>
<p>If it had "An African American writer", it would probably be technically correct, but it still sounds worse than C to my ears.</p>
<p>Perhaps that was a little incomprehensible, and if it was I'm sorry that I don't have a more cut-and-dried solution.</p>
<p>With these sentences, I just say them out loud in my head and see which one gets the intended point across without sounding unnatural.</p>
<p>It's becase the comma in D is unnecessary.</p>