In addition to being convenient, affordable, and versatile, legumes ar

OFFICIAL EXPLANATION


THE PROMPT AND THE OPTIONS


• Meaning? Structure?
This sentence is full of adjectives and noun descriptors. Find the verbs.
Intro phrase: Legumes have qualities A, B, and C
Main clause:
Legumes are full of D, E, F, and G
and
Legumes' antioxidant levels rival berries


• plus is not an acceptable conjunction on the GMAT, although plus is very common in spoken English and informal writing
• parallelism issue: in this sentence, rival is a verb that means equal (are equal to).
Two things are being compared. One is equal to the other.
RHS of comparison? berries
LHS of comparison? antioxidant levels
Logical nonsense. Antioxidant levels are not berries. We must compare things that are alike.
The sentence intends to compare levels of antioxidants in legumes to levels of antioxidants in berries.
Eliminate A


• In the idiom NOT ONLY X BUT ALSO Y, parallelism is violated.
• Often, as is the case here, we can just check the words right after not only and but also and make sure that X and Y are parallel
In this case, convenient (adjective} follows not only while ARE (a verb) incorrectly follows but also
convenient but also ARE. Not parallel

• Another way that will work every time: ONCE outside, TWICE inside.
If we have a verb such as ARE (or a preposition, or any word attached to the correlative conjunction NOT ONLY X BUT ALSO Y)
-- we find the root phrase,
-- note where, in the sentence, not only is placed, and
-- check words right before and right after not only (or but also)

Correct, ARE is once "outside":
Legumes ARE || not only [X] convenient, affordable, and versatile but also [Y] rich in fiber, vitamins, minerals, plant protein, and levels of antioxidants that rival those of berries. [Y] (once outside)

Correct, ARE is twice inside:
Legumes || not only ARE [X] convenient, affordable, and versatile but also ARE [Y] rich in fiber, vitamins, minerals, plant protein, and levels of antioxidants that rival those of berries. [Y] (Twice inside)

Wrong, ARE is once inside, once outside:
Legumes ARE not only [X] convenient, affordable, and versatile but also ARE [Y] rich in fiber, vitamins, minerals, plant protein, and levels of antioxidants that rival those of berries. [Y]
Option B follows this incorrect structure. X and Y are not parallel. Eliminate B.

• This sentence is a stylistic train wreck. (Don't decide on style first.)
• The definite article THE is ungrammatical unless we want to talk about exactly one group of legumes in one place at one time.
(We do not. This sentence is about legumes in general.)
• The legumes . . . are rivaling berries for antioxidant levels is nonsensical.
The legumes are in competition [with] berries to obtain antioxidant levels? Wow, that construction is horrible.
Eliminate C

• IDIOM?
Does not matter in this option.
We are allowed to use not only without but also
• ___ ING modifier (rivaling) is problematic
If we want to use it as a "contemporaneous event," it does not quite fit. It's different from the other "events." We read a lot about legumes and suddenly berries are at issue.
• a comma + participial modifier (a verbING modifier) of this sort often suggests a result.
--- ___ING words modify the preceding clause, subject of the clause, or immediately preceding word.
-- Well, rivaling is not modifying plant protein
-- This one is a tough call because something about this participial modifier is off.
-- Rivaling cannot modify the entire previous clause; that connection does not apply.
-- Rivaling can modify legumes (WHAT is doing the rivaling). This is close.
• parallelism?
Legumes are / rivaling?
I think that parallelism is the issue. "Rivaling" packs a heavy punch.
This way seems more parallel: legumes ARE blah blah, and RIVAL berries in blah blah. Are and rival are parallel.

KEEP D and compare to E


That works.
• Legumes have benefits that are listed properly in the "in addition" modifier
• Legumes have other benefits that are listed in the main clause ("are rich in")
• legumes rival berries in antioxidant levels. A little clunky, but okay because the word "legumes" is on one side of the parallelism marker, rival, and the word "berries" is on the other side of the parallelism marker.
• compared to D? Option E is better.

When a comma + ING seems not to fit properly, check parallelism.
Would the sentence be better if this seemingly "tacked on" ING word were a parallel verb?
Quite often the answer is "yes," as it is in this sentence.

GMAC uses this trap in which a participle (verbING) does not function as it should (or seems odd) and a parallel verb is available.

The correct answer is E

ISSUES

• IDIOM? We can use not only without using but also.
If we say not only and use but, though, the also must be there.

• ONCE OUTSIDE, TWICE INSIDE

I discuss "once outside, twice inside" in this post, here.

I will mark "outside" and "inside" with this symbol: ||
The verb ARE is the issue.
The words not only signal the beginning of a parallel structure.

-- the structure starts at the words not only

The "root" of this parallel structure is Legumes ARE.

When the verb (or preposition) comes before the idiomatic structure, we say that the verb ARE is outside the coordinating conjunction.
-- The verb should be outside ONE time, this way:
Correct: Legumes are || not only X but also Y
Correct: Legume are || not only A, B, and C, but also D, E, F, G, and H

If the verb ARE is "inside" the structure, it must be inside TWICE, this way:

Correct: Legumes || not only are X but also are Y (twice inside)
Correct: Legumes || not only are A, B, and C but also are D, E, F, G, and H. (twice inside)
In this case, the root is simply Legumes.

This sentence uses ARE once outside and once inside. Wrong.
Wrong: Legumes are not only X but also are Y (once outside, once inside)

COMMENTS

Okay, what is going on?
Option D is a very close contender, and yet the timer data tells me that D is only 1% of incorrect choices!
The other three are about 13% each! I am stunned.

This may be an instance in which too-rigid adherence to rules saved people.
I don't think so, though, if most of these posts are indicative.
In most of these posts, I sense discomfort with "rivaling" although not a lot of clarity about why.
And that fact is okay. Something about rivaling seems off.

Obviously, rivaling cannot be a "result" phrase. (What, because the legumes have all those other qualities, they rival berries in antioxidant levels? No.)
Rivaling cannot modify plant protein.
But what about legumes? Why not choose D on the basis that rivaling modifies the subject of the previous clause?
Answer: because that construction is not as good as the construction in E in which a "big" verb gets to be a verb rather than a weird participial modifier.
And that answer is all we need.

It just hit me. People are not picking D because they think that NOT ONLY must always be followed by BUT ALSO.
"Not only" can be in a sentence without "but also."

This question is harder than it seems.
These posts are good. Analysis is good, even if it is a little inaccurate here and there. Nice work. Kudos to all.