Scientists say that by bathing the skin cells in extracts of immune c

AndrewN GMATNinja
can u explain why option C is wrong

E wasn't the perfect answer for me, but after eliminating the others, it proved to be the best answer choice.

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saby1410 C isn't a complete sentence - behave as if immune system cells leaves the sentence hanging. I doubt this phrase would lead us to a logical sentence even if it is completed. Either way, C is wrong.

There's a modifier issue in (C). Take another look:


The modifier, "by bathing skin cells" seems to be describing "human skin cells." Unless we're envisioning some terrifying science fiction dystopia in which some skin cells bathe other skin cells, this is a illogical. It makes more sense to have "scientists" following the modifier, as they're the ones who'd be more likely to do experiments with human skin cells. The pronoun "they" in (E) refers to "scientists," so this is a better option.

I hope that helps!

Scientists say that, by bathing the skin cells in extracts of immune cells, that human skin cells in a test tube are made to behave as if they were immune system cells.

A) that human skin cells in a test tube are made to behave as if they were - that is incorrectly modifying immune cells

B) that human skin cells were to behave in a test tube as if they were - that is incorrectly modifying immune cells

C) human skin cells in a test tube were made to behave as if - use of as if is not n sync with how the sentence ends.

D) they have made human skin cells in a test tube that were behaving as - use of that were is incorrect and awkward

E) they have made human skin cells in a test tube behave as if they were - solves all the above issues, hence ans is E

OA solution :

Human Skin Cells

(A) Sentence Structure (that); Verb (are made)
(B) Sentence Structure (that); Verb (were to behave)
(C) Verb (were made); Modifier (as if)
(D) Modifier (that were behaving); Modifier (as)
(E) CORRECT

First glance

The original sentence begins with a subject-verb-that (Scientists say that), which should be followed by another clause, so this question is probably testing sentence structure. At the end of the choices, were is either present or omitted, so this split could be testing verbs, comparisons, parallelism, or sentence structure.

Issues

(1) Sentence Structure: that

After scientists say that in the non-underlined opening, two choices also begin with that. Check the sentence structure; does it make sense to repeat that?

By bathing … cells is a modifier set off by commas, so it can be ignored as you locate the core of the sentence. Eliminating some other adjectives and short modifiers, the core of the original sentence is:

(A) Scientists say that that cells are made to behave.

(B) Scientists say that that cells were to behave.

(C) Scientists say that cells were made to behave.

(D) Scientists say that they have made cells (that were behaving).

(E) Scientists say that they have made cells behave.

The second that is redundant and ungrammatical; eliminate (A) and (B).

(2) Modifier/Meaning: that were behaving

That were behaving is technically not part of the core of (D), as it is a modifier, but that difference alone is noteworthy. As a modifier, that must refer to a noun. The immediately preceding noun is test tube, which doesn’t make sense with were behaving; not only are test tubes incapable of behavior, but also the plural verb were does not match singular tube.

So, that were behaving actually “skips over” the modifier in a test tube, such that both modifiers describe human skin cells.

Now plural cells and plural were match, but there’s still a meaning problem:

In every choice but (D), the scientists caused the behavior of the cells in a test tube. In (D), the scientists just made cells, and those cells happen to behave a certain way. Eliminate (D).

(3) Verb: were to behave

The sentence cores above reveal an issue in (B): the verb made is omitted from both core and modifiers, changing the meaning of the overall sentence. In every choice but (B), scientists made cells (or, equivalently, cells were made by scientists). In (B), the scientists only do one thing: say something about cells; namely that the cells were (somehow supposed) to behave a certain way. Eliminate (B).

(4) Verb: are made; were made

As noted above, four of the choices use the verb made, but in different ways. Are made and were made are passive voice (the cells were passively made by scientists); have made is actively done by the scientists. Are made is present tense (passive), were made is past tense (passive) , and have made is present perfect (Active voice). Evaluate tense and voice.

The scientists say something, in the present, about the skin cells in a test tube, so the cells need to already exist. Past tense were made in choice (C) is acceptable, but the present tense are made is incorrect. Eliminate (A).

In addition, both are made and were made are in passive voice, which leaves some ambiguity: cells are/were made to behave by whom? The answer is probably scientists, but that’s made more clear in (D) and (E), where the active voice have made is paired with the subject they, which refers to scientists. The present perfect have made in (D) and (E) means the cells were made in the past, but they still exist. Passive voice is not automatically wrong, but there are enough concerns here to flag it; tentatively eliminate (A) and (C) for passive voice.

(5) Modifier: as if; as

There is a split between as if they were, as if, and as at the end of the choices. All of these are prepositional phrases, so it might be easier to evaluate the split between including they were and omitting those words.

First, when a pronoun is in some choices but not others, confirm the antecedent. They refers to human skin cells, both logically (human skin cells act like immune system cells) and structurally (human skin cells is the subject of the verb behave, which all the as phrases are modifying). So you can’t eliminate any choices based on the pronoun IN (e)

As if and as are adverbial modifiers describing how the skin cells behave. The verb were is needed to complete the comparison: verb as if noun is never right. For example, the cat chirped as if a bird is wrong, but the cat chirped as if he were a bird is right. Choice (D) has a similar problem, and also loses some of the intended figurative meaning without the if. Eliminate (C) and (D).

The Correct Answer

Correct answer (E) begins with they, which correctly and unambiguously refers to scientists. Starting the choices with a subject correctly allows the use of the active verb have made, which is also in the correct tense. At the end of the choice, as if they were correctly modifies how human skin cells … behave.

Hi AndrewN

I have a question in choice (E)

they (1) have made human skin cells in a test tube behave as if they (2) were

The first They refers to scientists, and the other refers to human skin skills.

Is it correct to use same pronoun refers to different noun ?

An expert told me that a pronoun cannot refer to different nouns. (I have used this rule since that time and it used to be correct)

Hello, Tanchat. You can use the same pronoun in a sentence to refer to a different noun as long as the perceived meaning of the sentence is clear. In SC specifically, you want to get behind the safest option of the five answer choices presented, and as GMATNinja often says, pronoun ambiguity is not a death sentence. (In fact, Mr. Ninja commented on the pronoun ambiguity in (E) in this post earlier in the thread.) If you come across a pronoun you think may be unclear, mark it as a doubt, but look for other, more obviously problematic issues before you remove that answer from contention.

- Andrew

Thank you, AndrewN

Actually, I read all comments. But, I am not sure that whether I can treat a pronoun which refers to different nouns the same as pronoun ambiguity ( even the perceived meaning of the sentence is clear ).
I understood. ✌️

Ps. Best explanation as always🙂,
Tan

Posted from my mobile device

Hi GMATGuruNY - how do you eliminate D ?

If “As” is used as a preposition. "As" as a preposition can be used in many ways, namely :
- In the role of
- Similarity / the same as / identical
- When I was

In this context, option D is using “As” as a preposition in the context to indicate similarity / identical / “the same as”
Ex # 1: I dance as Michael Jackson (implying, I am Michael Jackson)
Ex # 2: I dance as Michael Jackson does (implying, I dance like Michael Jackson dances)

In Option D – the usage of “as” is saying

Human skin cells were behaving as immune cells (implying Humans skin cells were immune cells) which is obviously wrong

That’s how I am eliminating D
Fair or you think wrong ?

Guiding principle:
Within a single clause, forms of the same pronoun -- they, them, their -- should have the same referent.

OA: Scientists say that they have made human skin cells in a test tube behave as if they were immune system cells.
In the BLUE clause, they = scientists
In the GREEN clause, they = human skin cells
Since the green they is in a separate clause from the blue they, the principle above does not apply.

Hi GMATGuruNY - how would you eliminate D ?

Scientists say that, by bathing the skin cells in extracts of immune cells, that human skin cells in a test tube are made to behave as if they were immune system cells.

A) that human skin cells in a test tube are made to behave as if they were -> "that" is redundant. Incorrect.

B) that human skin cells were to behave in a test tube as if they were ->same as A. Incorrect.

C) human skin cells in a test tube were made to behave as if -> "as" is used for clause comparison, so we need a verb post "as" and we don't have a verb. Incorrect.

D) they have made human skin cells in a test tube that were behaving as -> "were behaving" is incorrect tense.

E) they have made human skin cells in a test tube behave as if they were -> This is better. We can think of pronouns reference, but all pronouns refer to relevant nouns.

So, I think E.

Can someone explain me why Option C is considered wrong by stating that it is an incomplete sentence. Why concept of ellipsis as used in the comparison questions doesn't work here- ''As if '' implies (as if they were), since there is no verb tense shift (''were'' is already mentioned in the first clause, so it can be omitted.), thus implication should be valid. Is that concept of ellipsis only applys for X than Y type of construction?

Regards
Vighnesh

I doubt you will get a perfect answer to this Vighnesh, but yeah, in GMAT, ellipsis is largely limited to comparison sentences.

For example, following would be incorrect:

Peter became a Doctor because his father.

We cannot interpret this sentence as:

Peter became a Doctor because his father (became a Doctor).

Hello VIGHNESHKAMATH,

We hope this finds you well.

Having gone through the question and your query, we believe we can resolve your doubt.

The rule of ellipsis can only be applied if the verb in question has appeared earlier in the sentence. For example, "The living room has been cleaned, but the dining room has not (been cleaned)." - here, "been cleaned" can be omitted, only because "been cleaned" appeared in the first half of the sentence.

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