New, strong varieties of antibiotics

Though not a good Quality Question.

E seems the closest.
New, strong varieties of antibiotics show the potential to kill a harmful bacterium without the unintended effects of X and Y, which were unintended effects of earlier high-strength varieties.

I do share the concern with the usage of which in option E.

Agree with you about usage of "which" in E....but this is the OA as per Kaplan

Pretty sure this is testing meaning, not that/which

There's nothing grammatically wrong with D but the choice does 2 things that changes meaning.
1. It took out the information that killing benign bacteria and resistant strains were unintended effects
2. It then replaces it by saying that it was "required", which has different implications, as in the antibiotics were designed with the deliberate purpose of killing benign bacteria and to develop resistant strains.

Though I agree with you on the comparison part:
"The killing of benign bacteria" is indeed a complex gerund as it uses <article (a,the)> + <gerund> + <of preposition>. This construct can be treated as a noun that is being compared to another noun "the development of...". The parallelism is taken care of by this option.

Usage of which:
In my opinion, while is correctly used in this sentence; it has been treated as a subordinate (modifier) clause.
Subordinate clause:
Must begin with a connecting word (usually which or because) <tick>
should be a sentence fragment <tick> since it cannot stand on its own.
it does not effect the intent/meaning of the main clause. (does not contain main sub or verb) <tick>

'without...' is a verb modifier that starts with a preposition and the 'which...' clause when it's being treated as subordinate clause, gives information/ detail about it,hence 'which...' is placed correctly (adverb modifying 'without...' phrase, placed next to modifier).

Exactly what I thought Ankura! The complex gerunds before and after the 'and' (the killing of and the development ) are ultimately parts of a noun phrase. They arent noun themselves. I referred to the Manhattan SC guide they explicitly state that 'which' is to be used only to modify a NOUN immediately preceeding it. But the book also rightly mentioned that even GMAT makes the same mistake of modifying and entire clause with a 'which' in its own RC passages, something that even I noticed. So chances are KAPLAN goofed this SC up. The real GMAT would never be this ambiguous. So I think we should no longer bother about this question.

Cheers!

Based on the meaning, what the sentence is trying to convey is that new variety is better as it provides cure without the unintended side effects that were caused by earlier varieties. E makes this very clear, while all A, B, C and D have the same error of not making it clear that the side effects were caused by earlier varieties.

Can someone pls explain ? Is it not that which always modifies the noun immediately preceding it ?
If that is the case then which modifies 'bacteria' ... Pls help.

mikemcgarry

could you please provide your comments on this. how option E can be right here.
I think use of which is not right here. please clarify

Thanks

OA is Correct. Below is my take:

New, strong varieties of antibiotics show the potential to kill a harmful bacterium without the:
killing of benign bacteria and
development of resistant strains of bacteria
(both of), which were unintended effects of earlier high-strength varieties
Here there is no Parallelism Issue.
Parallel marker is : And
Killing of benign .. (Verb-ing of Noun) is parallel to development (Noun). This is one of the special case of parallelism and is very much acceptable in GMAT.

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