SalahT
C. Detergent manufacturers estimate that smaller containers will lower the wholesale price of laundry products by 7 percent next year and by 11 percent the following year.
E. By increasing the number of items on display shelves and the attractiveness of the presentations, discount stores hope to entice shoppers to spend more per shopping trip.
What is the source? If the source says the answer is E here, then I'd suggest finding better materials to work from. Answers A, B and D are clearly irrelevant. Answer C isn't a great answer, but if the plan will lead to lower expenses for the store, then the plan will increase the store's profits provided revenue stays constant (there's no basis to assume the savings will be passed on to the consumer; we're told nothing about how or if the retail price will change). But C is a much better answer than E, which just says "the stores hope the plan will work". Unless you believe in the power of positive thinking, it really doesn't matter what the stores "hope". If I planned to open an airborne car lot that sold cars suspended from hot air balloons floating over a city, my plan doesn't become more likely to succeed because "I hope the attractive presentation of the levitating cars will be enticing to car buyers". My plan will work or it won't based on how good the plan is, regardless of what I "hope" is true. Now, answer E would become a good answer if it provided evidence that the new displays would increase sales, but as written, it's logically worthless, so C is the only justifiable answer.
I think you yourself gave the answer of why C is wrong.
C option is actually incomplete because it can go in any direction, in favour or against the seller.