Until now, American cell-phone manufacturers enjoyed a large share of

Until now, American cell-phone manufacturers enjoyed a large share of the cell-phone market in China. However, Chinese manufacturers are becoming more productive, selling increasingly greater shares of new phones on the Chinese market. Therefore, American companies will see a diminishing share of the profits stemming from cell-phone sales in China.

Which of the following, if true, most seriously weakens the argument?

(A) Very few cell phones manufactured in China will be exported for sale in the United States.
(B) There are still more cell phone users in the United States than China, despite the latter's greater population.
(C) American companies still claim large shares of sales in China of other electronic devices such as computers.
(D) Many American cell phones are considered to be of superior quality to those produced by Chinese manufacturers.
(E) Cell phones manufactured by Chinese companies use many imported electronic components.