The new drug Prozac and the old one Elavil are about equally

The stimulus says "revenue from the sale of the new drug" i.e total revenues.
Option E does not weaken the argument, in fact, it does not alter the argument in any way, since we are concerned about the total revenues not the unit prices. If the number of units sold of the new drug (Prozac) more than that of the old drug (Elavil), the total revenues of the new drug will be greater.

Only option C gives a possible reason why consumers may not shift to the new drug. Since both share some side effects all consumers with those side effects have no reason to switch to the new drug (Prozac)

C is the best answer.

good explanation asandeep. Accepted!

I found answer E flawed. It could either strenghten or weaken the argument depending on the elasticity of the demand for this medicines (information for which is not provided).

What I mean is that a lower price always makes you sell more quantities of a product (law of demand), but total revenues depends on how much more you actually sell because of the decrease in price (elasticity).

Martin--

Just because the GMAT is a B-school test doesn't mean you're supposed to use that fancy brain of yours to apply economic principles.

This is a NOT WEAKEN question: So we need to find a option which in no way can harm the conclusion.

(A) Elavil is also used as a powerful anti-emetic medicine. -- Gives you a reason why Elavil might sell more and hence weaken the conclusion
(B) The Drug Control Authorities in six states have refused to allow the sale of Prozac till some more tests are carried out. -- Gives you a reason why Prozac might sell less and hence weaken the conclusion
(C) Some side effects of Elavil are common to Prozac as well. --Does not give any reason as to why Prozac may sell less or Elavil will sell more.
(D) Prozac is not recommended as an anti-depressant for diabetics and heart patients. -- Gives you a reason why Prozac might sell less and hence weaken the conclusion
(E) The unit sale price of Elavil is higher than that of Prozac. -- Gives you a could be reason why revenue from Elavil

Looks like it takes 2 real tests to start getting tough CRs right.
Ok, my way of thinking:

All of the following statements weaken the conclusion of the argument above, EXCEPT:

(A) Elavil is also used as a powerful anti-emetic medicine. << I have no idea what 'anti-emetic' means, but looks like Elavil can be used for other purposes as well, thus it still be on sale
(B) The Drug Control Authorities in six states have refused to allow the sale of Prozac till some more tests are carried out. <<weakens
(C) Some side effects of Elavil are common to Prozac as well. << we know this already from the stimulus. That info does weaken the conlusion, so that is the answer
(D) Prozac is not recommended as an anti-depressant for diabetics and heart patients. << clearly weakens
(E) The unit sale price of Elavil is higher than that of Prozac. << you replace a more expensive drug with a cheaper version. Chances are that sales volumes will be roughly the same. weakens

between C and E.
Went for E instead,since it leads you to believe that the drug 'E' wont be sold much.

C is basically a neutral answer option and hence correct.

Narrowed down to E and C and then selected E believing people will buy Prosac if its cheap.
Grrrr

The new drug Prozac and the old one Elavil are about equally effective in treating various forms of depression, although patients on the newer drug may have slightly fewer side effects. Thus, revenue from the sale of the new drug is going to far exceed the revenue from the sale of the old drug.

All of the following statements weaken the conclusion of the argument above, EXCEPT:

(A) Elavil is also used as a powerful anti-emetic medicine.
(B) The Drug Control Authorities in six states have refused to allow the sale of Prozac till some more tests are carried out.
(C) Some side effects of Elavil are common to Prozac as well.
(D) Prozac is not recommended as an anti-depressant for diabetics and heart patients.
(E) The unit sale price of Elavil is higher than that of Prozac.

Am not clear with the explanations provided hence, reopening this post..

IMO . E strengthens the conclusion. C is neutral and the rest weaken, since this is all weaken except question went for the one that strengthens. Please clarify why E os incorrect here

Will vote for C

Question : ALL Weaken : EXCEPT

Conclusion: revenue from sale of new drug(Prozac) exceed revenue from sale of old drug(Elavil)

P1 - both drugs equally effective
P2 - Prozac slightly few side effects

(A) Elavil is also used as a powerful anti-emetic medicine.
--> Weaken the conclucion (Elavil has some additional feature that is important and hence the sale of Elavil can be more - hence more revenue for old drug)

(B) The Drug Control Authorities in six states have refused to allow the sale of Prozac till some more tests are carried out.
--> Clear Weakens the conclusion (Claerly shows the ban on sale = loss of revenue)

(C) Some side effects of Elavil are common to Prozac as well.
--> No effect on conclusion (keep is a side)

(D) Prozac is not recommended as an anti-depressant for diabetics and heart patients.
--> Can weaken the conclusion

(E) The unit sale price of Elavil is higher than that of Prozac.
--> If unit sale price of Elavil is hight we can argue that revenue from Elavil is higher then Prozac
example: Elavil per unit profit might be : $2 compared to Prozac unit profile of 5 cent clearly the revenue from Elvial can be more hence weaken the conclusion

So ans should be C

Hi there is an assumption you are making in E, if the proces of the older drug is higher and ot has more side effects, naturally a customer will go for the new drug - Cheaperand Better ! so vols sold for elavil should go down and thus profits.. this strngthens

The official abswer is C. But i don't understand why?