Source GMAT prep 1:

Unlike using spices for cooking, in medicinal usage they are taken in large quantities in order to treast particular maladies

a) Unlike using spices for cooking, in medicinal usage they are taken

b) Unlike spices that are used in cooking, in using spices for medicine, they are taken

c) Unlike cooking with spices, taking spices for medicinal use is done

d) In cooking, small quntities of spices are used, whereas in medicinal usage spices are taken

e) In cooking, the usage of spices is in small quantities,whereas in medicinal usage they are taken

Why is E not the correct Ans?
How is comparison parallel in D?

In (D) - '...spices are used' and 'spices are taken' are parallel.
In (E) - '.. 'the usage of spices is small quantities' and '..in medical usage they are taken' are not parallel.

Tutor Pls give your perspective here.

choice e literally says that the usage of spices is 'in small quantities', which is not the proper message. this could mean that you don't use spices very often, but, when you do, you dump 14 kilos of allspice and 12 kilos of paprika in your pan.

the sentence needs to convey the message that the spices are the things of which quantities are small. choice d conveys this message well.

one could say that d isn't 100% parallel, but it's definitely more parallel than the other choices: in cooking, (noun) is used (passive voice construction); in medicinal usage, (noun) are taken (passive voice construction).

is there a faulty comparison in choice C?

Not quite. The comparison is cooking vs. taking: cooking spices vs. taking spices (for medicinal use). That's okay. The issue is that we can't say "taking spices is done in large quantities..."

in E, they has no clear referant... "spices" or "small quantities"?

you have a point, but sometimes there are official questions in which the correct answers actually exhibit a similar pattern of seeming ambiguity. for instance, check out this thread. in the correct answer, which is e, 'their' could technically refer to indications, cycles, or trees - but gmac doesn't regard this as a problem.

unfortunately, we're still working to nail down the exact situations in which ambiguity becomes, well, ambiguous. sigh...

In choice "e" why this sentence "the usage of spices is in small quantities" does not mean that the usage of spices are always is in small quantities when cooking? Why it need to be interpreted as you have mentioned " this could mean that you don't use spices very often, but, when you do, you dump 14 kilos of allspice and 12 kilos of paprika in your pan."? What is the "ambiguity/violation of grammer rule" that is making this sentence mean like what you have mentioned?

well, that's exactly the problem.

you need to strip down the sentence, to see exactly what single word is being described as 'in small quantities'. if you eliminate the prepositional phrase 'of spices', which just serves as an adjective in this sentence, you have the following:
[i]the usage ... is in small quantities'
that's wrong, because it's not the usage that's in small quantities; it's the spices themselves. (the sentence allows the possibility that the spices are used all the time - as long as the quantities are small.)

you need to have a sentence that correctly indicates that the spices are what's 'in small quantities'.

apart from this 'they' in E has no refferent.

is this a question? if so, i'm not sure what you're trying to ask; please state your question explicitly.
thank you.