Printwell’s Ink Jet Division manufactures ink-jet printers and the ink cartridges they use. Sales of its ink-jet printers have increased. Monthly revenues from those sales, however, have not increased, because
competition has forced  rintwell to cut the prices of its printers. Unfortunately, rintwell has been unable to
bring down the cost of manufacturing a printer. Thus, despite the increase in printer sales, the Ink Jet Division
must be providing the company with much smaller than it used to.
Which of the following, if true, most seriously weakens the argument?
A. Ink-jet printers in regular use frequently need new ink cartridges, and rintwell’s printers only accept rintwell’s ink cartridges.
B. Unlike some competing companies, rintwell sells all of its printers through retailers, and these retailers’ costs account for a sizable proportion of the printers’ ultimate retail price.
C. Some printer manufacturers have been forced to reduce the sale price of their ink-jet printers even more than rintwell has.
D. In the past year, no competing manufacturer of ink-jet printers has had as great an increase in unit sales of printers as rintwell has.
E. In the past year, sales of rintwell’s ink-jet printers have increased more than sales of any other type of printer made by rintwell.
Answer: C/A
请问为什么选A啊？没有理解！ | 
