In Nystrom V

In Nystrom v.Trex Company,where Nystrom sued Trex for patent infringement on an exterior flooring board,the appeals court held that:

A) Nystrom's patent failed for obviousness,so there was no fringement
B) Nystrom's patent failed because it was prior art,so there was no infringement
C) Nystrom's patent failed because it was already in use in other countries
D) there was no infringement because the Trex process was sufficiently different
E) none of the other choices