-ing form Vs Infinitve (Source : CatPrep)

[bellthecatnow]

Combining atoms at room temperature may be possible one day, but such a feat has never been verifiably performed.

(A) Combining atoms at room temperature may be possible one day
(B) One day, it may be possible to combine atoms at the temperature of a room
(C) The combination of atoms at room temperature may one day be possible
(D) It may one day be possible to combine atoms at room temperature
(E) Combining atoms at room temperature may one day be possible



OA = D

Please suggest how D is correct here? What does 'such a feat' refer to?

[RonPurewal]

Combining atoms at room temperature may be possible one day, but such a feat has never been verifiably performed.

(A) Combining atoms at room temperature may be possible one day
(B) One day, it may be possible to combine atoms at the temperature of a room
(C) The combination of atoms at room temperature may one day be possible
(D) It may one day be possible to combine atoms at room temperature
(E) Combining atoms at room temperature may one day be possible



OA = D

Please suggest how D is correct here? What does 'such a feat' refer to?

"such a feat" refers to the combining of atoms at room temperature (the only feat mentioned in the problem).

since this is not a pronoun, it doesn't have to refer to a single noun. (for another example of this sort of reference, see "a shortcoming" in #59 in the purple verbal supplement.)

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in any case, i don't think i understand your question. what do you think is incorrect in (d)?