Unlike most gynodioecious plants, the male and female Catasetum orchid

I think so yes. In parallelism, it is essential that both the elements are in same format. Noun with Noun and Adj with Adj. So comparison of Reynolds with a blue Trimax would be incorrect.

I believe you CAN use adjectives in comparison. The statement "Unlike Reynolds, blue Trimax costs more!" should be correct but would have a different meaning than the second sentence.

In this first sentence, you are comparing Reynolds to a specific variant of Trimax i.e. blue Trimax (Assumption being there exists only one variant of Reynolds), whereas in the second sentence you are comparing a variant of the Reynolds with a variant of Trimax.

Experts' Global Official Explanation:

Comparison + Meaning

Understanding the intended meaning is at the core of getting this question correct; the intended meaning of this sentence is that Catasetum orchids differ from most other species of gynodioecious plants, in that it is very easy to distinguish between the male and female Catasetum orchids.

• Comparison must always be made between similar elements.

A. Trap. This answer choice incorrectly compares “most gynodioecious plants” to “male and female Catasetum orchids” rather than with the species “Catasetum orchids”; thus, Option A incorrectly implies that most gynodioecious plants are difficult to distinguish among, while the male and female Catasetum orchids are easily distinguishable.

B. Trap. This answer choice incorrectly compares “most gynodioecious plants” to “the gender of the Catasetum orchids” rather than with the species “Catasetum orchids”, incorrectly implying that most gynodioecious plants are difficult to distinguish among, while the male and female Catasetum orchids are easily distinguishable; the intended meaning of this sentence is that Catasetum orchids differ from most other species of gynodioecious plants, in that it is very easy to distinguish between the male and female Catasetum orchids.

C. Trap. This answer choice suffers from a pronoun error; the pronoun “those” has no clear antecedent. Additionally, Option C incorrectly compares “those in most gynodioecious plants” to “the male and female Catasetum orchids”, illogically implying that “the male and female Catasetum orchids” are easy to distinguish between, unlike the “male and female Catasetum orchids” of most gynodioecious plants; the intended meaning of this sentence is that Catasetum orchids differ from most other species of gynodioecious plants, in that it is very easy to distinguish between the male and female Catasetum orchids.

D. Correct. This answer choice correctly compares the species “Catasetum orchids” to “most species of gynodioecious plants” through the use of “Catasetum orchids are unlike most species of gynodioecious plants”, conveying the intended meaning of the sentence- that Catasetum orchids differ from most other species of gynodioecious plants, in that it is very easy to distinguish between the male and female Catasetum orchids.

E. Trap. This answer choice incorrectly compares “most gynodioecious plants” to “male and female Catasetum orchids” rather than with the species “Catasetum orchids”, incorrectly implying that most gynodioecious plants are difficult to distinguish among, while the male and female Catasetum orchids are easily distinguishable. Further, Option E incorrectly uses "unlike in most gynodioecious plants" to modify "to tell the male and female Catasetum orchids apart", illogically implying that most gynodioecious plants contain male and female Catasetum orchids, which are difficult to tell apart; the intended meaning of this sentence is that Catasetum orchids differ from most other species of gynodioecious plants, in that it is very easy to distinguish between the male and female Catasetum orchids.

Note: Answer choice D is not perfect as the usage of pronoun “it” is avoidable; however, GMAT often tests you with questions where no answer choice is convincing and one has to select the best among the five choices. This question is a pure inspiration from an official question; in interest of simulating all kinds of challenges that GMAT may throw at you, we need to, at times, include such borderline controversial questions as well.

D is the best answer choice.

Question, what if A had instead said:
(A) Unlike most gynodioecious plants, the male Catasetum orchids and female Catasetum orchids are very easy to tell apart.

Would that be correct?

Hello cyrwr1,

We hope this finds you well.

To answer your query, your version of Option A would not be correct.

"the male Catasetum orchids and female Catasetum orchids" is just a lengthier version of the phrase "the male and female Catasetum orchids", so the comparison remains the same.

We hope this helps.
All the best!
Experts' Global Team

Experts' Global Video Explanation:

Hi team
Can below question be explained


Unlike most gynodioecious plants, the male and female Catasetum orchids are very easy to tell apart.

(A) Unlike most gynodioecious plants, the male and female Catasetum orchids are very easy to tell apart.
(B) Unlike most gynodioecious plants, the gender of the Catasetum orchids is very easy to distinguish.
(C) Unlike those in most gynodioecious plants, the male and female Catasetum orchids are very easy to distinguish.
(D) Catasetum orchids are unlike most species of gynodioecious plants in that it is very easy to tell the male and female apart.
(E) It is very easy, unlike in most gynodioecious plants, to tell the male and female Catasetum orchids apart.

Regards
Vitusha

Hello, Vitusha. I was getting ready to comment on what a clever question this was, and then I realized it was a plagiarized design from the following official question (found here). Compare:

Changing a handful of words but testing the same material in the same way is not clever and is in violation of copyright law. I would encourage you and others who may stumble upon this thread to study the official question that this one was so clearly taken from. If you read through that other thread and still have questions, feel free to call upon me personally. I would be happy to help you.

Good luck with your studies.

- Andrew

Need? That is a false statement, akin to someone saying he needs, at times, to cheat because the material in a certain course is challenging and too expansive. There is a difference between inspiration and copyright infringement. (Such cases are brought to court all the time in the music industry.) You cannot tweak a few words from an official question, test the same concepts in the same way in each answer choice, and call it an inspired question. It is a thinly veiled official question, one that can give a test-taker a false sense of security if he or she comes across the official question down the road and answers quickly and confidently, perhaps without knowing why.

It is difficult to produce high-quality questions, and I doubt any test prep company would have the same kinds of resources to throw behind their own questions as GMAC™ does. I also know that questions such as the one above are rampant in the industry. However, I would encourage you at Experts' Global to set your sights on creating original material, with no official question serving as a template. If that happens, I will be the first in line to get behind your efforts.

- Andrew