This a flaw question--similar to a weaken question. The plan is to attract first-time customers with coupons they can use at any retailer. Consider each choice:

(A) This is correct. If the coupons lead retailers to make choices that make it less likely first-time customers will buy the company's products, the coupons will have been counter-productive and the plan will have failed.
(B) This choice suggests a way in which the company will make the plan more likely to succeed.
(C) Like (B), this is another bit of evidence that suggests the company's plan is likely to succeed.
(D) This choice addresses a possible problem, but claims that employees will be trained to handle coupons like the ones on which the company's plan hinge.
(E) This supports the plan's likelihood of success. If first-time buyers are influenced by price, a coupon would make them more likely to choose the company's products.