manishankar wrote:18. A peculiar feature of the embryonic mammalian circulatory system is that in the area of the heart the cells adhere to one another, beating in unison and adopting specialized orientations exclusive of one another.
(A) beating in unison and adopting
(B) they beat in unison while adopting
(C) beat in unison, and adopt
(D) beating in unison yet adopting
(E) even though they beat in unison and adopt

Comments: The correct answer as per the 1000 SC's document is D, however I feel option D disturbs the parallel structure partly formed by the underlined part
Option C seems more appropriate to me

Any thoughts.......

Contrast needs to be setup between adhere to one another,beat in unison and adopting...
Hence we need "yet" to bring in that contrast.

pick D

I believe that the primary difference between 'C' and 'D' is rooted in the third word of the sentence - feature.

If we choose 'C', the sentence would then specify multiple features, whereas the sentence is supposed to specify only one feature:

...the cells adhere to one another, beat in unison, and adopt specialized orientations exclusive of one another

In choice 'D', the one feature being specified is that cells adhere to one another. There's no issue of parallelism (or lack thereof) between adhere and beating because the latter is modifying the former, and not appearing as its own feature.

However, the parallelism between beating and adopting is correct.

This brings me to choosing 'D' vs. 'A'. I believe 'D' is preferable because the phrase adopting specialized orientations exclusive of one another belies the feature of cells adhering to one another. Therefore, the usage of "yet" is correct.

Thanks Tomada, the explanation answers my doubt.
"Feature" VS "Features". I missed this part and thought

the cells adhere to one another, beat in unison, and adopt specialized orientations exclusive of one another

are all parallel structures. But now i am convinced

Also kvcpk highlighted the contrast that is required, which requires "YET" instead of "AND" in the underlined part of the statement

Thanks a milliion guys

Warm regards,
Mani