Writing Question

<li>2008 Apr 17</li>

<p>Every day, millions of tiny stony bits falling quietly into the atmosphere, burning briefly as meteors, and leaving behind a vaporized residue that filters ** slowly** to the Earth. </p>

<p>Taken from the Chinese link on <a href="http://talk.collegeconfidential.com/sat-preparation/1265035-my-progress-thread-31.html#post13780108%5B/url%5D"&gt;http://talk.collegeconfidential.com/sat-preparation/1265035-my-progress-thread-31.html#post13780108&lt;/a&gt;&lt;/p>

<p>Answer key says (A) falling but I don't think it would correct the parallel structure problems in the sentence. Thanks in advance!</p>

<p>It's A because the word 'falling' causes a sentence fragment.</p>

<p>So basically, the phrase 'burning briefly as meteors, and leaving behind a vaporized residue" is two subordinate clauses? Is the comma necessary? (Well, I suppose it's necessary. It just really confused me haha. It makes me think it's a series.)</p>

<p>And "Millions fall" would be the simple subject and simple predicate?</p>

<p>Yeah, that's basically it.</p>