Critical Reasoning

Hi,

would you explain me what mistake I did when I answered A or B ? The answer is E

The program to control the entry of illegal drugs into the country was a failure in 1987. If the program had been successful, the wholesale price of most illegal drugs would not have dropped substantially in 1987.
The argument in the passage depends on which of the following assumptions?

(A) The supply of illegal drugs dropped substantially in 1987.

(B) The price paid for most illegal drugs by the average consumer did not drop substantially in 1987.

(C) Domestic production of illegal drugs increased at a higher rate than did the entry of such drugs into the country.

(D) The wholesale price of a few illegal drugs increased substantially in 1987.

(E) A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price.

Let's take a look at this one:

Accoding to the supply/demand drugs' prices should have been increased instead of dropped, so we need to find out a reason why it was not the case:

(A) The supply of illegal drugs dropped substantially in 1987. The paragraph is telling you this...not good enought

(B) The price paid for most illegal drugs by the average consumer did not drop substantially in 1987. Out of scope, the parragrap does not talk at all about the average consumer

(C) Domestic production of illegal drugs increased at a higher rate than did the entry of such drugs into the country. Perhaps, but this answer goes to far assuming something we don't knwo for sure, and in GMATland we cannot do that
(D) The wholesale price of a few illegal drugs increased substantially in 1987. Nope it did not

(E) A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price- YES, there must have been another reason other than the drop in demand of illegal drugs to make the prices drop

IMO E

situation : A program to control entry of the illegal drugs failed.prices of illegal drugs dropped in the country.

conclusion: Program's failure led to dropped prices.

ASSUMPTION REQUIRED: failure of the program led to entry of more illegal drugs[ i.e, increased supply of illegal drugs]
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reasoning : Since low prices attract customers, we can assume that prices could have dropped [ by illegal drug-sellers to make profit]either because toomuch of supply is there or because no demand is there.

Option E is a restatement of the above,

(E) A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price......meaning that " increased supply [due to program's failure] is also one of the causes...

a continuation of the above question....

The argument in the passage would be most seriously weakened if it were true that
(A) in 1987 smugglers of illegal drugs, as a group, had significantly more funds at their disposal than did the country’s customs agents
(B) domestic production of illegal drugs increased substantially in 1987
(C) the author’s statements were made in order to embarrass the officials responsible for the drug-control program
(D) in 1987 illegal drugs entered the country by a different set of routes than they did in 1986
(E) the country’s citizens spent substantially more money on illegal drugs in 1987 than they did in 1986

OA:B

this is "defence" assumptiom. pls, read CR bible.

I like the explanation on E.