SC: A new hair-growing drug is being sold for

[cesar.rodriguez.blanco]

I do not know how to deal with this SC:
What are the erros in the different answers?

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

[sunny.jain]

IMO: D

we often say that "double the price of"...i think price of is correct usage.

[chuckberry007]

I think is B. Being being sold for three times the price "than" the drug maker charges for another product.

[RonPurewal]

please search the forum. this problem has already been posted on 2-3 other threads.

the longest is here:
a-new-hair-growth-drug-is-being-t5504.html