Official Explanation
Conclusion: "We should definitely continue to enforce this policy during the fall in order to keep sales high."
Premises: "Last summer, our company instituted a new policy that required retailers to order a minimum quantity of our new tablet device or else receive no products at all"; "Although we lost some potential retailers, we ended up selling many more products than would reasonably have been expected."
Assumption: The plan to continue boosting sales using a minimum order requirement will succeed if continued during the fall; there are no problems with this plan.
Malcolm's argument uses a planning structure, because it begins by identifying a problem: the company wants to continue selling higher than expected numbers of its new tablet device in the fall, just as it did over the summer. Next, Malcolm proposes a plan to achieve that goal: continue enforcing a policy that requires that retailers buy a minimum number of devices on each shipment, or receive no product.
A planning argument always assumes that the plan will work, and that there are no problems with the plan. An answer choice that weakens the argument will suggest a reason the plan will not work, or point out a potential problem with the plan.
Weaken's Malcolm's
The first answer choice is out of scope; the argument is concerned with the number of tablets sold by the company to the retailers, not with the prices charged by the retailers to the customers.
The second answer choice simply restates information from the premises; the argument already notes that some potential retailers were lost (the ones who were unable or unwilling to order a minimum amount). This answer choice does not point out any problem with the plan.
The third answer choice is out of scope; whether many small retail stores carry most of the company's other electronic devices is irrelevant to Malcolm's argument, which pertains only to the company's new tablet device.
The fourth answer choice does not weaken Malcolm's argument, which is concerned only with whether requiring a minimum order quantity will continue to increase sales in the fall, and not whether potential customers have purchased from the company before.
The fifth answer choice weakens Malcolm's argument. If the retailers' summer orders have left them fully stocked with tablets for the fall, then they will have no need to order additional tablets, regardless of the company's policies.
The sixth answer choice does not weaken Malcolm's argument, and in fact may strengthen it: if sales in the fall quarter of the year are usually higher than in the summer, due to holiday shopping, then the retailers may need to buy additional products in the fall.
Answer: The retailers' summer orders have left them fully stocked with tablets for the fall
Weaken's River's:
The first answer choice does not weaken River's argument, and may in fact strengthen it. River's argument is concerned with whether increasing the price of the device would be successful; if retailers charge a wide variety of prices, this may mean that the price has some flexibility in it.
The second answer choice simply restates information from the premises; River's argument already notes that the tablet device is not widely available.
The third answer choice is out of scope; whether many small retail stores carry most of the company's other electronic devices is irrelevant to River's argument, which pertains only to which stores carry the company's new tablet device, and the price to be charged for it.
The fourth answer choice weakens River's argument, because River's argument assumes that the customers are like her – that they are avid fans and long-time customers, and therefore will happily pay a higher price for the tablet device. If many potential customers have never purchased from the company, then they may not be willing to pay a higher price.
The fifth answer choice does not weaken River's argument, and in fact may strengthen it. If the retailers' summer orders have left them fully stocked with tablets for the fall, the company's only remaining strategy might be to open sales up to other, smaller retailers.
The sixth answer choice does not weaken River's argument, and in fact may strengthen it: if sales in the fall quarter of the year are usually higher than in the summer, due to holiday shopping, then a higher price might be successful.
Answer: Many potential purchasers of the company's tablet have never purchased a product from the company before.