a parallel structure with “and” wouldn't make sense here, because these two descriptions are not separate and independent. (in the structure “x and y”, the “x” and “y” should be two separate, relatively independent things.)
when you first read the sentence, you should notice that the second description -- the description about a bunch of stuff frozen from top to bottom -- is elaborating on, or illustrating, the first description (too cold to support life). therefore, for the sentence to make sense, the second part should be written as a modifier of the first part.



the gmat doesn't test punctuation, so you shouldn't worry overly much about issues of punctuation.



no, that's still very incorrect.
first, those structures shouldn't be parallel in the first place; see my explanation above.
second, you've turned “considered far too cold…” into a modifier that is modifying … nothing that makes sense. (if that construction is a modifier, then the only thing that it can logically modifier is europa.)
third, the sentence is also unidiomatic in a couple of ways, but i will refrain from discussing those because gmac has announced that it doesn't test random idioms anymore.

--

a reminder:
don't try to fix the sentences!

even though this section of the test is called, ironically, “sentence correction”, you do not need to be able to fix the sentences; you only need to be able to select the correct answer choice from the choices given.
trying to fix the sentences is an irrelevant skill set; if you do too much of this, it will distract you from the skill set that you actually need. moreover, most users' attempts to fix sentences create numerous other errors (like the three new errors mentioned above), many of which are outside the scope of the gmat.

if you want extra practice using correct constructions, DO NOT rewrite the current sentences; instead, make your own (much simpler) examples that use those constructions.

Ron,

sorry for bringing up this issue again but I am not able to see clearly why C) is wrong in spite of your explanation.

I see "Europa has long been considered too cold and has water thought to be frozen." (Parallel)

I do agree with the fact that those two things are not 100% logically parallel. I mean, the consideration is not actually something that Europa has (in terms of possesion). But I wouldn´t be able to find a reason to dismiss this choice.

I see it even more clear put the other way round: "Europa has water thought to be frozen and has long been considered too cold."

Many thanks!

the problem is the word "as", which you left out in your transcription but which the original poster acknowledged as a fatal mistake almost immediately at the beginning of the thread. please read the posts carefully before you ask a question that has been answered already..

_________________
Tim Sanders
Manhattan GMAT Instructor

Ron, How to identify verb and participles? Most of the times i fail to identify these in parallel constructions. Also how to gauge whether verb form is eligible to be verb or participle?

if you can't tell verbs and participles apart, then that's symptomatic of a much deeper problem: you aren't thinking about what the words actually mean when you read them.
past-tense verbs and participles have meanings that are essentially complete opposites -- the former suggests that the noun actually does the action, while the latter suggests an action done to the noun -- so, if you can't reliably tell them apart, then you must not be thinking much (if at all) about the meaning of the words.

for instance:
robots made (= verb) today's breakfast --> this is something that the robots did.
millions of robots made (= participle) in korea are shipped to the u.s. each year --> this is something done to the robots.

Thanks Ron for your text. sorry if I am asking some insane questions...
Is this similar to active and passive voice constructions?

active voice :robots made today's breakfast.
passive voice : today's breakfast was made by robots. ->here made is participle.

so is that past participle are used in passive voice constructions only?

essentially, the meaning of the past participle is passive, yes.