Sentence Correction

While the thorns of all roses are protective, dissuading predators from feeding on the flowers' blooms, unlike roses that grow in temperate climates, though, the thorns of desert roses also serve as reservoirs for water to forestall the ever-present threat of dehydration.

A) While the thorns of all roses are protective, dissuading predators from feeding on the flowers' blooms, unlike roses

B) All roses' protective thorns dissuade predators from feeding on their blooms; unlike those

C) The thorns of all roses are protective, dissuading predators from feeding on the flowers' blooms; unlike those of roses

D) While all roses' thorns are protective, they dissuade predators from feeding on the flowers' blooms; unlike those of roses

E) The thorns of all roses are protective and dissuade predators feeding on their blooms, however, unlike those

OAC

Why notB

Please explain.

GMATsid2016 wrote:While the thorns of all roses are protective, dissuading predators from feeding on the flowers' blooms, unlike roses that grow in temperate climates, though, the thorns of desert roses also serve as reservoirs for water to forestall the ever-present threat of dehydration.

A) While the thorns of all roses are protective, dissuading predators from feeding on the flowers' blooms, unlike roses

B) All roses' protective thorns dissuade predators from feeding on their blooms; unlike those

C) The thorns of all roses are protective, dissuading predators from feeding on the flowers' blooms; unlike those of roses

D) While all roses' thorns are protective, they dissuade predators from feeding on the flowers' blooms; unlike those of roses

E) The thorns of all roses are protective and dissuade predators feeding on their blooms, however, unlike those

A: unlike roses that grow in temperate climates, though, the thorns
B and E: unlike those that grow in temperate climates, though, the thorns
Semantically, those seems to stand in for roses (since it would be nonsensical to refer to THORNS that grow in temperate climates).
As a result, all three options seem to compare THE THORNS to ROSES THAT GROW IN TEMPERATE CLIMATES -- an illogical comparison.
Eliminate A, B and E.

Generally, an introductory while-modifier must serve to introduce a clause that OPPOSES the main clause.
D: While all roses' thorns are protective, they dissuade predators
Here, the red clause does not oppose the main clause but SUPPORTS it, expressing HOW thorns dissuade predators.
Thus, the usage of while is illogical.
Eliminate D.

The correct answer is C.

GMATGuruNY wrote:
B) All roses' protective thorns dissuade predators from feeding on their blooms; unlike those

Dear GMATGuru,

In choice B, 'unlike' does it refer to the noun before semicolon 'blooms' or the noun in the beginning of first sentence'thorns' ???

Thanks for your help

Mo2men wrote:

GMATGuruNY wrote:
B) All roses' protective thorns dissuade predators from feeding on their blooms; unlike those

Dear GMATGuru,

In choice B, 'unlike' does it refer to the noun before semicolon 'blooms' or the noun in the beginning of first sentence'thorns' ???

Thanks for your help

A complete sentence follows the semi-colon:
Unlike those that grow in temperate climates, the thorns of desert roses also serve as reservoirs.
Since this portion constitutes a new sentence, those should serve to stand in for the subject that follows (the thorns):
unlike THORNS that grow in temperate climates.
As noted in my post above, however, the semantic intention is for those to refer to ROSES:
unlike ROSES that grow in temperate climates.
Another error in B is the discrepancy between the grammatical implication of those and its semantic intention.