It's A.
This problem is clearly based on the "giant fungus in the forest of Michigan" problem in OG-11 (sorry I forget which number that item is; I can look it up later if necessary), and the same solution applies.
The key here is that "persisting" is parallel to "created". In other words, this part of the sentence means the same as "the atoms and molecules that were created in the progenitive explosion and that persist in even the emptiest regions of space."
You may be wondering how an -ed form (a past participle) can be parallel to an -ing (a gerund). Well, even though they don't *look* very similar to each other, they're considered parallel in terms of their grammatical function. They're both adjectives formed from verbs. The -ing form is sometimes even called the "present participle," so you can see the similarity to the "past participle." So in other words, combinations like "recently lost and still missing," "shot and bleeding," or "diversified and growing" are all parallel.
B is wrong because it would have incorrect verb agreement.
C is wrong because it wouldn't be parallel -- C is a past tense form, which superficially *looks* like the past participle "created" but isn't the same kind of grammatical thing. "created" in this sentence is a participle, like "broken" or "thrown," not a past tense verb.
D is wrong because the subject 'they' makes this clause not parallel to anything else in the sentence. It can't be parallel to "that comprise the atoms and molecules... etc." (think of it this way -- could you say 'particles tha comprise the atoms and molecules created in the progenitive explosion and _that_ they persist..."??) And "they persist" is clearly not parallel to "created" either.
E "are persisting" is awkward and a strange choice of verb tense -- "are persisting" uses present progressive tense, which is used for temporary situations, things that are going on right around now but not for too much longer. It makes it sound like these particles are just hanging around for a little while -- the opposite of what the sentence is saying.
