While the battalion was engaged in the Battle of the Bulge, its bravery under fire was not unlike that of its Russian counterparts, who fought off the Germans at the Siege of St. Petersburg.

(A)not unlike that of its Russian counterparts, who fought
(B)not like its Russian counterparts, who fought
(C)like its Russian counterparts and their fight
(D)like that of its Russian counterparts for fighting
(E)as that of its Russian counterparts, who fought

A is using double negatives - not unlike... doesn't that make it the "not to be preferred choice"? Between A and E, I chose E.

Yes, the answer is certainly A. You can confirm this from an OG 10 question given below whose OA is A. Therefore, I don’t think we need to entertain any doubts the authenticity of the double negative ‘not unlike’, since it has been already accepted by OG.



The problem with using ‘as’ for comparing nouns is that, it is often taken to be comparing X in the role of Y. For example, X is very good as a captain, meaning that X is very good in the role of the captain or X is very good as a finisher, meaning that he is very good in the final few slog overs. One might notice that the true essence of comparison is lost when ‘as’ is used for comparison between nouns. That is why E is not to be preferred over A.

The second point to note about this topic is that per se, the pronoun ‘its’ stands for the battalion’s. Its bravery is being compared with the bravery of Russian counterparts. It is not clear to which country does the battalion belong to. It could be Britain or France or for that matter any other country. You might see, the original OG does not mention ‘its’ and avoids the unnecessary doubts. . This is just an observation.
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(A)not unlike that of its Russian counterparts, who fought
(B)not like its Russian counterparts, who fought ( wrong comparison)
(C)like its Russian counterparts and their fight (wrong comparison)
(D)like that of its Russian counterparts for fighting
(E)as that of its Russian counterparts, who fought