Gasoline-poweredboat engines manufactured in the a North American country ... ...

Which one of the following statements, if true, most seriously undermines the argument?
(A) Water from the various oceans cannot be accurately divided among nations because ocean currents travel thousands of miles and cross numerous national boundary lines.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Nova Press: Set C - Premise / Conclusion Practice