enniguy wrote:

mittalashwani13 wrote: Could you pls share the source of this question? Thanks.

GMATPrep.

nitya34 wrote:good Q..

read Ron's expl in Manhattan forum

Also, Nitya, I think Manhattan have removed all OG and GMATPrep related posts. I couldn't find them. I would really like to see Ron Purewal's explanation. If you do have the link, please post it here.

Thanks again everyone.

hi.

we didn't remove anything. the old OG folder is still up, but posting in it has been disabled since 12/7/07.

you can still post GMATPREP problems on our forum; in fact, the GMATPREP folders have, by an enormous margin, the most traffic on our whole forum.

a new hair-growth drug is being sold for three times the price, per milligram, as the drug's maker charges for another product with the same active ingredient.

A. as
B. than
C. that
D. of what
E. at which

OA: C

this one isn't that bad if you get down to the "skeleton" of the sentence. to do that, you should kill intervening prepositional phrases that don't affect the grammar of the main sentence.
to this end, you can simply get rid of the following:
"per milligram"
"for another product"
"with the same active ingredient"
and you're left with:
a new drug is being sold for three times the price ____ the drug's maker charges.
once you see this, it should be more clear that (c) is the correct answer. if you're a non-native speaker and you can't recognize "that" as the word belonging in that blank, then here's the reason: it's because "price" is the direct object of "charges". when you turn around such constructions, you use "that":
i hit the ball --> the ball that i hit
she delivered the baby --> the baby that she delivered
etc.