The reasoning is quite straight-forward. Because coupons attract customers and make them try your brand item, turning them loyal towards your brand, so Hartman should also do the same.
But is it so simple in the real world ?
Is there a guarantee attached here that if this normally happens, this will also happen for the Hartman's product ?
What if there is some condition, which we are not aware of and which needs to be fulfilled for the observation made above to be true.
Looking at options :
A) This option sort of pushes forward what is given as a basis in the passage. It hints that some incentive is necessary for the customers. So , it mildly supports the idea that if Hartman gives coupons, customers' attention can be drawn. Incorrect choice as it is not a weaken statement.
B) This option tells us that if you give coupons to customers, those who use them and try your product, are actually non-loyal customers. So this means it is not a guarantee that these customers will stay loyal to Hartman. This goes against the conclusion and is a possible correct choice.
C) This option tells us that if you offer coupons of say 10 percent discount, the grocery stores will increase their value such that the discount actually offered will be 20 %. Given the basis on which the conclusion was drawn, it seems more likely that customers will be attracted with more power and force than before. This option seems to support the conclusion because it says that grocery stores will actually help in promoting the product further. Hence, incorrect choice.
D) Typically only one third coupons are redeemed. But does that mean no coupons are redeemed ?
Atleast some customers are going to become loyal ones, aren't they ?
This option gives only a statistic proving that the coupons will be used, though only upto 30%.
Doesn't weaken the argument and hence incorrect.
E) This option tells that to get most effective results, tv ads should also be added to coupon campaign. But does that mean the coupon method is not at all effective. May be it is not the most effective, but it is effective to some extent, say 30 to 40 %. Even then, customers have turned loyal. This option does not seem to weaken the conclusion. Incorrect choice.
Correct choice should be B.