Sentence Correction (SC) | Re: Possible long-term consequences of the greenhouse effect,

"possible" is already mention in the sentence, you dont need 'may'..its redundant.

so A,B and C are out.
the melting of polar ice caps and the rising sea level

Melting :- Gerund
Rising : Adjective.

E is parallel because of
melting of PIC :- Prepositional phrase
the rise in sea level :- Prepositional phrase.

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