My son had the following question on a SAT review. I chose the right answer, but I am having trouble explaining why I chose it.

Can you help us out? The answer is "A" which I would replace as "fall", but then it doesn't agree with the rest of the series with the words "burning" and "leaving"?
Here's the question:
The following sentence contains either a single error or no error at all. If the sentence contains an error, select the one underlined part that must be changed to make the sentence correct. If the sentence contains no error, select choice E.
Every day, millions of tiny stony bits
falling (A) quietly into the atmosphere, burning briefly
as (B) meteors, and leaving
behind (C) a vaporized residue that filters
slowly (D) to Earth.
No Error (E)Thank You! Laurie :-)