Laboratory rats and mice live up to 40% longer than usual when fed a

1. Here "that" is a relative pronoun that creates a copy of a noun previously used (diet).

2. Then the relative pronoun "which" creates a clause ("which they would normally eat) that modifies that copy ( i.e. the relative pronoun "that"). This relative pronoun "which" is again the object of the clause modifier. Thus the complete construction becomes:

".. that which they would normally eat..."

The above construction is awkward since the above two functions can be more concisely carried out using one single relative clause starting with "that". The usage would then be "....that they would normally eat...".

This correct construction is used in option D, but there even the relative pronoun "that" is omitted because by virtue of parelleism it is allowed to drop repeated word(s) from the second element of two parallel items being compared, if the meaning is not obscured. Hence the final construction becomes:
"....that they would normally eat..." ("that", i.e. "diet" has already been used in the first item in the comparison structure and is therefore dropped).

Laboratory rats and mice live up to 40% longer than usual when fed a diet of at least 30% fewer calories than that which they would normally eat, but that otherwise contains all necessary vitamins and nutrients.

a)of at least 30% fewer calories than that which they would normally eat, but that otherwise

'A diet of X' implies that X is the actual thing being consumed. Rats can be fed a diet of insects, worms, etc. But I can hardly imagine a rat feasting on a delectable meal of 30% fewer calories.

b) with at least 30% fewer calories than what they would normally eat though otheriwse it

The 'it' is not necessary. To test this simply omit the 'it' and notice how the verb 'contains' unambiguously refers to diet.

c) that has at least 30% fewer of the calories than they would normally eat, but otherwise it

The same problem as (B).

d) that has at least 30% fewer calories than they would normally eat but that otherwise

'They' clearly refers to 'rats'. The 'but' sets up the necessary contrast. And there is no unnecessary 'it'. Therefore, (D) is the answer.

e) that has at least 30% fewer calories than that which they normally eat, though that otherwise

(E), like (A), implies that the rat is eating the 'diet'. Notice how 'that' refers to a diet - "than (the diet) they would normally eat."
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I choose D for the sake of parallelism. diet that.... but that

sanghar 's point is also correct - the pronoun should be "those" since it refers to "calories". The comparison apparently becomes faulty otherwise. (Why I used "apparently" is discussed later in this post)

Wrong (apparently): The diet has 30% less calories than that (the diet) they would normally eat. (apparently wrong comparison "diet" with "calories")
Correct: The diet has 30% less calories than those (the calories) they would normally eat. (correct comparison "calories" with "calories").

Now, why I used "apparently" above:
Alternatively "diet" could be used in a different way to maintain parallelism:
The diet has 30% less calories than HAS that (the diet) they would normally eat.
But again by virtue of parallelism "has" can be omitted.
The diet has 30% less calories than has that (the diet) they would normally eat.

So, "that" and "those" both are correct, but the construction of the sentence changes (and since the construction is omitted it does not matter whether "that" or "those" is used).

Laboratory rats and mice live up to 40% longer than usual when fed a diet of at least 30% fewer calories than that which they would normally eat, but that otherwise contains all necessary vitamins and nutrients.


(A) of at least 30% fewer calories than that which they would normally eat, but that otherwise - than THAT which they would normally eat
a diet...THAT otherwise contains all necessary nutrients
The first that refers to the DIET NORMALLY EATEN BY RATS.
The second that refers to the DIET THAT HAS FEWER CALORIES but otherwise contains all necessary nutrients.
Within the context of a single modifier, the same pronoun -- THAT -- cannot serve to replace two different referents (the two different diets).

(B) with at least 30% fewer calories than what they would normally eat though otherwise it - "Diet with" is unidiomatic ; the usage of what conveys that rats normally would eat something OTHER THAN CALORIES.
As a result, B illogically compares CALORIES to something OTHER THAN CALORIES

(C) that has at least 30% fewer of the calories than they would normally eat, but otherwise it - Option B and C seem to imply the following contrast:
Laboratory rats live longer, EVEN THOUGH their diet contains all necessary nutrients.
Not the intention.
The intended meaning is as follows:
Laboratory rats live longer when fed a diet THAT contains all necessary nutrients.

(D) that has at least 30% fewer calories than they would normally eat but that otherwise - Correct

(E) that has at least 30% fewer calories than that which they normally eat, though that otherwise - same as A

Answer D
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But isnt it wrong to say ......'calories than they'???? isnt tht comparing calories with 'they'-the rats??

a)of at least 30% fewer calories than that which they would normally eat, but that otherwise
"That which" refers to the diet, whereas we're comparing the # of calories
b) with at least 30% fewer calories than what they would normally eat though otheriwse it
"diet with" is not a correct idiom. "What" seems unnecessary, too.
c) that has at least 30% fewer of the calories than they would normally eat, but otherwise it
Wrongly compares calories with "they" (mice).
d) that has at least 30% fewer calories than they would normally eat but that otherwise
1) ...."that"... "that" is in parallel
2) There is only one antecedent to "they". Although "calories" is closer, it doesn't make sense for "calories" to refer to "they".
e) that has at least 30% fewer calories than that which they normally eat, though that otherise
- just for fun, this one's solely wrong because "otherise" is misspelled

Option A:
Two relative pronouns ("that which") one after the other is awkward (though grammatically not incorrect).
"diet of 30% ..." is awkward - "diet of..." is generally used to specify particular foods - e.g., "diet of non-vegetarian foods", "diet of curd-rice" etc.

Option D:
Yes, ideally "than that" is to be used. However as has been frequently observed, GMAT allows omission of repeated words form the second element of a parallel structure.

The following post is more detailed:
laboratory-rats-and-mice-live-up-to-40-percent-longer-than-130331-20.html#p1703220

Laboratory rats and mice live up to 40% longer than usual when fed a diet of at least 30% fewer calories than that which they would normally eat, but that otherwise contains all necessary vitamins and nutrients.

(A) of at least 30% fewer calories than that which they would normally eat, but that otherwise
- Uses 'that' twice to refer to different items
- Compares calories vs diet
- Eliminate

(B) with at least 30% fewer calories than what they would normally eat though otherwise it
- Compares calories vs (what = not calories)
- Eliminate

(C) that has at least 30% fewer of the calories that they would normally eat, but otherwise it
- Uses the word 'fewer' without using the word 'than'
- Eliminate

(D) that has at least 30% fewer calories than they would normally eat but that otherwise
- Keep

(E) that has at least 30% fewer calories than that which they normally eat, though that otherwise
- Uses 'that' twice to refer to two different items
- Compares calories vs a diet
- Eliminate

the simplest way to attack E is, on GMAT, "which" cannot be used without a COMMA. That's enf to ding answer choice E!

HTH

Excellent. That is exactly what I am looking for. Can you please explain if there is any difference between:
Rats are fed a diet of at least 30% fewer calories than they would normally eat --> Compare sentences
and
Rats are fed a diet of at least 30% fewer calories than that which they would normally eat --> Compare DIET

I do not think that the 2nd sentence is wrong.

Are "though otherwise" and "But otherwise" correct usage?

IMO D

Laboratory rats and mice live up to 40% longer than usual when fed a diet of at least 30% fewer calories than that which they would normally eat, but that otherwise contains all necessary vitamins and nutrients.


(A) of at least 30% fewer calories than that which they would normally eat, but that otherwise

(B) with at least 30% fewer calories than what they would normally eat though otherwise it

(C) that has at least 30% fewer of the calories than they would normally eat, but otherwise it

(D) that has at least 30% fewer calories than they would normally eat but that otherwise

(E) that has at least 30% fewer calories than that which they normally eat, though that otherwise

Diet should be followed by that so A and B out
Fewer of calories is wrong so C out
In D and E
D compares the old diet and the new diet appropriately --> that has at least 30% fewer calories than they would normally eat also D follows parallelism

Posted from my mobile device

Hello, Mavisdu1017. I see that you have already received a few responses above, but since you followed up with me by PM, I will add my thoughts on the matter. First of all, I wrote a lengthy post on as _____ as comparisons a few months back, and I think it may prove useful to you. In that article, I encourage people to test a given comparison to see whether it yields a reasonable interpretation, even if some words seem to be missing. We should employ the same strategy here, rather than looking to apply some supposed rule or another without much thought. Also, if you can find any reason, comparison or no, to doubt an answer choice, you should mark that doubt. It is okay to be unsure of certain matters, but you want to keep moving.


It could just be me, but I have major reservations about when fed a diet of... calories. I am not sure whether of can work on its own in this context, since calories do not appropriately describe what the animals were fed. My doubt would be removed entirely with another word to qualify the diet, as in consisting of. In terms of the comparison, that must refer to diet, and which must be used as the relative pronoun because in English, we do not stack that pronouns, as in ... than that that they would normally eat. It is a grammatical peculiarity. So, is the comparison inherently unsound? I do not think so. There are times in which a modifier may be applied to a noun ahead of the object of a preposition—see the following questions from the Official Guide: LINK 1, LINK 2, and LINK 3—and I see no reason why a comparison could not adhere to a similar tendency. The that preceding otherwise is difficult to follow. Since the sentence uses of earlier instead of that, it appears as though that at the end of the underlined portion is commenting on the normal diet, rather than on the calorie-restricted diet.

1) {a diet that} they would normally eat

2) but {a diet} that otherwise contains all necessary vitamins and nutrients

Compare:

1) a diet of at least 30% fewer calories

2) but {a diet} that otherwise contains all necessary vitamins and nutrients

If nothing else, we have to question the lack of parallelism if the second interpretation is intended. In short, I would see off the original sentence for a diet of calories and everything that that of entails.


A diet with fewer calories? This might be a more functional preposition than of on its own—e.g., a library with 30 percent fewer books as opposed to a library of 30 percent fewer books—but I still feel as though it could be improved. Luckily for us, we see a glaring target in it at the end of the underlined portion. The latter half of the comparison reads, {the diet} they would normally eat though otherwise {the diet} contains... We can take the time to sort out what we think the sentence is driving at, or we can search for a more reasonable alternative.


Two things stand out to me here. First, of the is entirely unnecessary within the comparative fewer calories, so this answer choice is already on shaky ground. Then, the same it pops up that I objected to before. I will save my discussion of the comparison for the next answer choice, but here, there is a noticeable lack of clarity at the end:

{Animals live longer} when fed a diet that has at least 30% fewer {calories} than {the diet/the calories that the animals} would normally eat, but otherwise {the diet} contains all necessary vitamins and nutrients.

We should understand that it refers to the first diet mentioned, the calorie-restricted diet, but that is not apparent on first read.


I would argue that the comparison and subsequent resolution of the sentence is clearer without being explicit, or, in other words, by omitting just what would follow than. Check for a reasonable interpretation:

1) a diet that has at least 30% fewer calories than {the calories that} they would normally eat

2) a diet that has at least 30% fewer calories than {the diet that} they would normally eat

I prefer the second interpretation, since, strictly speaking, animals do not eat calories (but can be said to consume some quantity of them), and it is true that in this sort of context, the exam would typically repeat a verb or use a substitute in an appropriate form of to do, but what we have to ask ourselves is whether either interpretation is unsound. Is it incorrect to omit a verb in a basic comparison between a diet that has more or less of something than another diet? I would say no. The context of this sentence allows us to appreciate that one aspect of a diet is being compared to that same aspect of another diet without being explicitly mentioned, and perhaps the author felt it would be less clear to use both would... eat and has or does. That is admittedly a judgment call, one that I imagine a native English speaker would not think twice about, but I suppose the takeaway is not to apply your understanding of comparisons too narrowly. At least the two parts of the sentence that comment on the calorie-restricted diet are better connected by way of the grammar:

a diet that has X but that otherwise contains Y

Again, I think the above sentence is easier to follow than one that said,

a diet that has fewer calories than the X that {the animals} would normally eat but that otherwise contains Y

Perhaps the point I have been aiming to make on clarity makes more sense now. In short, I see no compelling reason to eliminate (D), even if it takes some liberties.


If we work out the logic of this sentence, it follows a similar pattern as the one above:

a diet that has fewer calories than the X that {the animals} would normally eat, though that otherwise contains Y

The parallelism that links the beginning with the end is much harder to spot, and it is difficult to find any justification for the presence of the comma + {al}though. You would not think a similar-meaning word to but would make that much of a difference, but it is much easier to follow the iteration of the sentence that answer choice (D) creates than this one.

There you have it. I am not sure whether you feel any better about comparisons, but perhaps this question has taught you that you cannot let your guard down. Just when you think you have everything figured out, another sentence will come along and challenge your preconceived notions of what a correct sentence should look like.

- Andrew
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Thank you for the kind words, PyjamaScientist. You can rest assured that if you see a certain verb used across all five iterations of a sentence in SC, such usage is acceptable. Another use of would is to convey a regular action from the past.

Every Monday, I would get out of bed to face another week of school.

The simple past got does not immediately cue the reader that the following action is habitual. Consider the sentence if every Monday were placed a little deeper in the sentence:

I got out of bed every Monday to face another week of school.

In short, you may want to revisit your two-pronged application of would. The word can be far more useful. I will include references to my two most often consulted resources for SC:

1) Dictionary.com definition

2) Cambridge Dictionary definition

(I feel validated. I see just the usage I referred to in both.) Thank you for following up.

- Andrew
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hey guys

I have a question about construction of "that which they" or "that which"

Is this construction fine to use?

Has there been any correct GMAT questions that have that and which next to each other? This structure seems a bit odd to me.

Thanks

Laboratory rats and mice live up to 40% longer than usual when fed a diet of at least 30% fewer calories than that which they would normally eat, but that otherwise contains all necessary vitamins and nutrients.
Why is A wrong?
Aren't they comparing two diets? In that case "than that" is required.
Am I wrong?

Hi sayantanc2k

Wanted to clarify one point - the omitted relative pronoun after "than" in the corrected sentence shouldn't be "that", but should be "those" as it is supposed to be referring to "calories", in keeping with the meaning? I have indicated this below:-

Laboratory rats and mice live up to 40% longer than usual when fed a diet that has at least 30% fewer calories than they would normally eat but that otherwise contains all necessary vitamins and nutrients.

Laboratory rats and mice live up to 40% longer than usual when fed a diet that has at least 30% fewer calories than those (the calories) they would normally eat but that otherwise contains all necessary vitamins and nutrients.

The antecedent of "that" is a diet, and the diet is the direct object of the phrase "they would normally eat." This construction is impressively confusing. I never thought you could remove a direct object but indeed, if the meaning remains intact, there ought to be no issue at all.