Gas hydrates, chemical compounds of water and natural gas, are increas

Hey All,

I get asked by PM to take this one on, so here I am. How goes it?

Gas hydrates, chemical compounds of water and natural gas, are increasingly being studied for their potential to be huge reservoirs of energy, possibly causing sea floor instability, and significant contributors to global warming.

This question is about parallelism versus modifiers. We don't really want any modifiers here, so we have to get rid of answer choices that try to spin it that way.

A. to be huge reservoirs of energy, possibly causing sea floor instability, and
PROBLEM: Commas set off lists or modifiers. If it's a list, it's already unparallel (to be huge, causing, significant are not parallel). Modifier doesn't make sense either, however, as "causing" would be modifying the previous clauses. The fact that the hydrates may be reservoirs of energy is not causing sea floor instability, so that's out.

B. to be huge reservoirs of energy, possibly causing sea floor instability, and even as
PROBLEM: Same as above on every level.

C. as huge reservoirs of energy, possibly causing sea floor instability, and
PROBLEM: Same as above.

D. as huge reservoirs of energy, and the possible cause of sea floor instability,
PROBLEM: You only use COMMA followed by "and" at the end of a list of more than three things, not just two. Also, now the final section has become an appositive modifier. This is because the list MUST have ended after the "and", so the comma must be setting off a modifier. Because it's just a noun at the end, it could only be a noun modifying a noun ("Thomas Jefferson, our nation's third president, was awesome."). Obviously, the "instability" is not a "significant contributor to global warming"

E. as huge reservoirs of energy, as possible causes of sea floor instability, and even as
ANSWER: Look at the lovely parallelism "as, as, as", plus it finally makes sense!

Hope that helps!

-t