To entice customers away from competitors, Red Label supermarkets have

Strategy: Give discounts on home appliances to customers who spend $50 or more on any shopping trip to Red Label.
Aim of the strategy: To entice customers away from competitors
Result: cash register receipts of $50 or more are up thirty percent since the beginning of the program. (So before the program, if there used to be 100 receipts of >$50, now there are 130 receipts of >$50)

Claim of executives: the discount program has been a huge success

Were they able to entice customers away from competitors, we don't know. Receipts of >$50 are up, we understand. But are those extra 30% due to new customers, we don't know.
Weaken the claim so find something that tells us that this jump is not because of new customers. That the program did not succeed in its aim.

(A) Most people who switched to Red Label after the program began spend more than $50 each time they shop at Red Label.
This could mean that there were some new customers. It is possible that some increase is due to old customers bumping up their bills but it is also possible that some increase is due to new customers too.

(B) Most people whose average grocery bill is less than $50 would not be persuaded to spend more by any discount program.
This implies that the old customers will not bump up their bills. So new $50 receipts could be because of new customers joining in.

(C) Most people who received discounts on home appliances through Red Label’s program will shop at Red Label after the program ends.
Irrelevant. What happens after the program ends is not under discussion yet.

(D) Since the beginning of the discount program, most of the people who spend $50 or more at Red Label are people who have never before shopped there and whose average grocery bill has always been higher than $50.
This shows that the program was actually a success. New customers were enticed to shop at Red Label since most of the $50 receipts came from new customers.

(E) Almost all of the people who have begun spending $50 or more at Red Label since the discount program began are longtime customers who have increased the average amount of their shopping bills by making fewer trips.
This weakens the claim. So most people who averaged $50 or more were old customers. They used to shop every week at Red label and total say $30 per week. Now, they shop once every 2 weeks and total $60 per trip. So that is why the >$50 receipts have increased.
So this shows that the program may not be a success.

Answer (E)­