Sentence Correction

Synthetic oil burns less efficiently than natural oils do.

A. Synthetic oil burns less efficiently than natural oils do.
B. Synthetic oil burns less efficiently than does natural oil.
C. Synthetic oil burns less efficiently than natural oil.
D. Synthetic oils burn less efficiently than natural oils do.
E. Synthetic oils burn less efficiently than do natural oils.

C IMO.

Since we are discusing differnt types of oil here , we shud use singular i guess.

jaxis wrote:C IMO.

Since we are discusing differnt types of oil here , we shud use singular i guess.

hint--> we are discussing burning, although it's the disguised discussion...

IMO : C
What's the source?

source: GMAT Club-verbal notes by Nguyet Minh.
It's an open question - I don't have an answer. Per my understanding, we are comparing not the oils themselves but how the two oils burn; we should compare burning effects.

I would go gor B ...........

Could we have an expert opinion on this please. I have also seen it here and there , but didnt get satisfactory answer.

Night reader wrote:Synthetic oil burns less efficiently than natural oils do.

A. Synthetic oil burns less efficiently than natural oils do.
B. Synthetic oil burns less efficiently than does natural oil.
C. Synthetic oil burns less efficiently than natural oil.
D. Synthetic oils burn less efficiently than natural oils do.
E. Synthetic oils burn less efficiently than do natural oils.

its just between B and C and i chose B

diebeatsthegmat wrote:

Night reader wrote:Synthetic oil burns less efficiently than natural oils do.

A. Synthetic oil burns less efficiently than natural oils do.
B. Synthetic oil burns less efficiently than does natural oil.
C. Synthetic oil burns less efficiently than natural oil.
D. Synthetic oils burn less efficiently than natural oils do.
E. Synthetic oils burn less efficiently than do natural oils.

its just between B and C and i chose B

my frank opinion <B> uses inversion after /than/ and this may hurt the parallel structure of comparison - even if we compare burning effects
<C> compares oils, as said above
I would go with <D> - although the first part becomes plural, the whole sentence doesn't through any doubt on parallelism between two actions: the 1st is plural, so too is the second; no inversion issue is involved after /than/ as in <B> and not illogical comparison is made as in <C>

But I would request experts to shed light on this entry.

I am between B & E

Paulrichards wrote:I am between B & E

both in B and E - subject+verb /than/ verb+subject <-- inversion
I'm not sure these are the right choices, as inversion is optional and allowable in any case. So by clicking B or E we can't really determine here what's the best
Therefore I chose D!

I think, this part is very tricky - trade-off, may be it's around 99% difficulty, who knows... simple sentence, but how many tensions

Night reader wrote:Synthetic oil burns less efficiently than natural oils do.

A. Synthetic oil burns less efficiently than natural oils do.
B. Synthetic oil burns less efficiently than does natural oil.
C. Synthetic oil burns less efficiently than natural oil.
D. Synthetic oils burn less efficiently than natural oils do.
E. Synthetic oils burn less efficiently than do natural oils.

Okay: The "inversion" NightReader discussed does not matter and can't differentiate between right answers on the GMAT. Repeat: the "inversion" of word order in the comparison does not matter. Not only on the GMAT, but in any proofreading manual, (D) and (E) above are exactly the same in terms of correctness.

In fact, the only one that seems wrong above is (A), and even that (singular/plural comparison error) isn't enough to eliminate a choice for certain on the GMAT. The argument against (C) is that it drops the verb in the second part of the sentence, but this is okay. In fact, it is true that we're comparing oil-to-oil in all five choices; the only reason the verb is necessary is that, sometimes, the two compared things can be nonparallel in terms of sentence structure. For example:

"Furnaces burn synthetic oil less efficiently than does natural oil."

The above sentence is clearly wrong -- the reason is that "natural oil" is acting as a verb's subject, making it parallel to "furnaces," which is an illogical comparison. Since "synthetic oil" is a verb's object, natural oil needs to be as well:

"Furnaces burn synthetic oil less efficiently than they do natural oil."

Note that another wrong version of the sentence would be "Furnaces burn synthetic oil less efficiently than natural oil," because it would be ambiguous as to which of the above scenarios is in fact the case.

However, in the original question posted by Night Reader, there's only one noun in each part of the sentence -- oil. Thus it doesn't matter that, in (C), this ambiguity might exist; the second "oil" is automatically parallel to the only other noun in the sentence, "oil," -- each is the subject of the verb "burns," which is implied/ellipsed in the latter part of the sentence.

Thus, (C) is the most concise and still correct, so on test day, I'd choose it. That being said, this would never appear on the GMAT, since 4 of the 5 answers are more or less interchangeable in terms of correctness. I would recommend looking at ALL four examples here as potentially correct options; on the real test, you'd only see one of these four possibilities (although it equally well be any of them!) among the answers, and that would be the correct construction of a comparison.

Just switched back to SC forum from PS/DS
Thanks Adam and the BTG fellows for close participation - I've almost over-out-mis- used parallel+inversion here
I too hope not to see such kind of query on GMAT

IMO : C