Most bird species sing despite lacking vocal chords compenating with

OFFICIAL EXPLANATION



• HIGHLIGHTS

Absolute phrase
The correct answer to this question contains an absolute phrase.
I explain how to spot such phrases after the POE.

Pronoun ambiguity?
In the correct answer, no pronoun ambiguity exists, although I can understand why you might think so.

This guideline governs pronoun ambiguity: A pronoun must have only one logical antecedent.

• If NO noun exists as a possible antecedent, we have a case of The Missing Antecedent, not pronoun ambiguity.

• If one noun is logical as an antecedent but disagrees with the pronoun in number or gender, we have a case of Noun-Pronoun Disagreement, not pronoun ambiguity.

• If more than one noun qualifies as an antecedent, but one noun makes more logical sense than the other, we do not have pronoun ambiguity.

• If two or more nouns qualify as logical antecedents for the pronoun, we have true pronoun ambiguity.

If I am absolutely certain that pronoun ambiguity exists, I eliminate the option.
If I am even slightly doubtful about whether ambiguity exists, I keep the option and hope to find a better answer.

MEANING?
Most bird species do not have vocal chords, but they can sing by vibrating the the muscles and membranes in their throat.
Air from the lungs passes over the vibrating muscles and membranes and generates sound.

THE PROMPT

• The first part of the non-underlined part of the sentence is an independent clause followed by a comma but not a conjunction (and, but, or).
-- The second part of the sentence cannot be an independent clause.
-- Two independent clauses may be joined by:
(1) comma + conjunction
(2) a semicolon (which could be followed by a word such as however or therefore ["conjunctive adverbs"])

• No option gives us a conjunction. Whatever follows that comma is a modifier—and one that might sound strange.
• The second part of the non-underlined portion commits us to something that is parallel to generating (sound waves)

THE OPTIONS


• the pronoun "their" could refer
-- to most bird species (that are using their throat muscles) or
-- to throat muscles and membranes or
-- to vocal chords
• "for their absence" is weird. This sentence suggests that the birds are responsible for the birds' own absence. (Or the vocal chords' absence? The phrase is ridiculous.)
Eliminate A


• as in (A), the pronoun their has two different referents in the same sentence.

• The phrase vibrating for their absence is babble.
-- The birds' throat muscles and membranes vibrate in order to compensate for the absence of vocal chords.
-- The construction implies that the throat muscles and membranes vibrate for the purpose of their absence (the birds? the muscles and membranes?)
The meaning is illogical.
Eliminate B


• as in A and B, the pronoun their has two antecedents and is ambiguous
• The phrase being compensated for their absence is illogical. The throat membranes and muscles to do not receive compensation (payment or restitution!) for vibrating.
Eliminate C


• I see no errors
• in this option, their shows up once and does not create ambiguity as in A, B, and C because
-- only one noun is a logical antecedent for their: most bird species
-- vocal chords do not have throat muscles.
• we have a very long absolute phrase that modifies the entire idea of the main clause
-- Main clause: Most bird species sing despite lacking vocal chords
-- Modifier (absolute phrase): their throat muscles and membranes compensating for the absence by vibrating and generating sound waves when air from the lungs passes over them.[/i]

• with respect to the absolute phrase, notice the structure
(1) pronoun/noun + noun modifiers
(2) no working verb.
-- a working verb is a verb that you could put into a main clause.
Working verb: The birds sing.
Not a working verb: The birds singing.
-- ___ING words by themselves are not working verbs.
When I say "by themselves," I mean "not coupled with a helping verb such as IS or ARE."
Working verb: The birds are flying..
Not a working verb: The birds flying.

• An easy example of an absolute phrase to remember and use for comparison if you are confused

-- One example of an absolute phrase in MGMAT Sentence Correction is
His head held high, Owen walked in the room.

His head held high modifies "Owen walked into the room."

-- I highlighted a present participle in our option (D) (compensating) and the past participle in the simple example (held) because absolute phrases often contain participles (verbING or verbED words).
KEEP

[/quote]
• this one is a gift. Eliminate it immediately because an absence that vibrates is utter nonsense.
Do not waste your time analyzing with compensation.
The absence vibrates? No.
Eliminate E

The best answer is D

• NOTES

Correct option D uses an absolute phrase.
The phrase their throat muscles and membranes compensating for the absence by vibrating and generating sound waves when air from the lungs passes over them
modifies the idea in the main clause: Most bird species lack vocal chords.
The absolute phrase is not fancy, just long. The absolute phrase tells us more about the fact that most bird species lack vocal chords.

You do not need to worry about the jargon.
You just need to understand how these modifiers work.
They are fairly rare on the GMAT.

When you face a question in which none of the answer choices seems to include an appropriate clause or phrase, you may need to look for an absolute phrase hiding in one of the choices.

Absolute phrases
(1) often seem disconnected from a sentence
(2) consist of a noun/pronoun + noun modifiers (almost always participles or adjectives )
(3) do not contain a working verb
(4) modify (give information about) the whole idea of the main sentence
(5) often seem "stuck onto"the sentence.

Absolute phrases are not clauses. (Absolute phrases contain no working verbs. All clauses contain working verbs.)

Absolute phrases do not create "comma splices."
Comma splice: I enjoyed the delicious food at dinner, my friend made me laugh.
-- comma splices occur when two full independent clauses are "stuck together" with only a comma
-- independent clauses must be connected by [comma + conjunction] or a semicolon.
Occasionally a colon will connect two ICs, though only the first sentence must be an independent clause.
The president's behavior is appalling: using nasty tweets, he attacks people who are testifying under oath.

Takeaways: if you see a noun/pronoun + noun modifier [e.g., their throat muscles and membranes compensating . . .]
(1) that seems sort of "slapped onto" the sentence, and
(2) that modifies the whole main clause,
and everything else is correct, assume that you are dealing with an absolute phrase.

See whether the sentence is similar to
His head held high, Harold walked into the room.
OR (example with a present participle)
His head never drooping, Harold walked into the room.

COMMENTS

syedmohammad211 , welcome to SC Butler.

I am pleased.
You all did exactly the right thing. You eliminated options and lived with (D).
Your mission is to eliminate the four worst answers.
Mission accomplished.
Remember to explain. Could someone relatively new to studying SC understand what you are talking about? Could that person use your explanation to solve a similar question?

These hard questions can make people feel nervous about posting.
Try not to worry so much. Be willing to be wrong.

This statement might sound silly, but most people have to practice being wrong.
You can condition your nervous system not to freak out at mistakes.
Practice doing so, because almost all of you will make more than a few mistakes on the GMAT.

A couple of these explanations are outstanding.
Everyone: nice work.
Kudos to all.