A new hair-growing drug

[sparsh.21]

A new hair-growing 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 is D

Please expain

[revoltangel]

I think it's because...

Of what makes the proper comparison.

Ex: "She charges 3x of what he charges"

As is usually used for comparing similar things
Ex: "She charges as much as he does"

Than and that don't fit with the structure of the sentence unless it was "the drug is being sold for three times more than the price that the drug's maker charges"

Hope this helps. I think this is more of an idiom/diction problem.

[mjjking]

there's something wrong with this sentence.

idiom should be: for three times as much as the price charged by the maker".