Which of the following is an assumption on which the argument depends?
I think the answer is option A Conclusion : The argument says that since the number of new card holders did not go up the customers are not taking advantage of discounts on the card.
Pre thinking : Maybe the existing customers are taking advantage of the discount and there is an alternate reason for the number of card holders not increasing. So we need to look for an alternate reason for the number of card holders being the same.
(A) Few if any of the additional FoodMart locations that opened between 1990 and 1995 served customers who signed up for FoodCards.
This could be our alternate reason. The new stores dont serve the customers with discount card and that is why the number is not going up.
(B) In 1995 most Palmonters who lived within 10 miles of a FoodMart did not have a FoodCard.
Irellevant
(C) Offering discount programs such as the FoodCard does not decrease the profit margin of a grocery store.
Out of scope
(D) In 1995 Palmonters who did not have FoodCards usually chose to shop at grocery stores other than FoodMart locations.
This just strengthens the conclusion
(E) The discounts offers to FoodCard holders in 1995 were not the same at all FoodMart locations.
Discount is not the same at all stores but that should not be a reason for number of cards not increasing. customers may shop less but the number of cards should have increased irrespective.