Here's the
official explanation provided by the GMAC for this question:
The given sentence cites a finding that improvement of agricultural stock breeding requires that buildings be adapted to animals, not animals to buildings. The given sentence is not well-formed; in following
adapted with the verb form
adapting, which does not fit with the verb form
must be in the first portion of the construction using
rather than, it fails to preserve a required parallelism in verb form. The phrase
rather than adapting …
buildings errs in suggesting
confinement buildings as the implicit subject of
adapting.
Option A: This answer choice fails for the reasons explained above.
Option B: The phrase
the adaptation of is nonparallel to
adapted. The wording confusingly suggests that
the adaptation of animals to buildings is being presented as an alternative to
animals, or perhaps to
confinement buildings.
Option C: The verbal form
to be adapted is not appropriately parallel to
adapted and does not fit with the verb form
must be in the first portion of the construction using
rather than. The wording confusingly suggests that
animals to be adapted to buildings is being presented as an alternative to
animals, or perhaps to
confinement buildings.Option D: Correct. In this answer choice, the passive verb form
adapted is implicit:
animals [adapted] to buildings. This phrasing fits with the verb form
must be in the first portion of the construction using
rather than. So the parallelism with the earlier occurrence of
adapted is preserved, and the sentence is coherent and grammatically correct.
Option E: The preposition
instead of could be used in place of
rather than, but the parallelism requirement, noted for
rather than would also apply to use of
instead of. The phrase
animals adapting to buildings is illogically nonparallel to
buildings must be adapted to animals.
The correct answer is D.
Please note that I'm not the author of this explanation. I'm just posting it here since I believe it can help the community.