Sentence Correction (SC) | Re: Gas hydrates, chemical compounds of water and natural gas,

Potential to [verb], potential as [noun]. Both are correct idioms, given the verb "be" with "potential to" or the noun clause "huge source of energy" with "potential as"
Everything boils down to parallelism; (E) is the only answer choice where all three elements of the list are parallel "As huge sources....as possible causes...as significant contributors"

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