Radon is a harmful gas found in the soil of certain regions of the United States. A statute of the state of Magenta requires occupants of residences with basements susceptible to the intrusion of radon to have their residences tested for the presence of radon and to take specified remedial steps if the test indicates the presence of radon above specified levels. The statute also provides that the testing for radon may be done only by testers licensed by a state agency. According to the statute, a firm may be licensed to test for radon only if it meets specified rigorous standards relating to the accuracy of its testing. These standards may easily be achieved with current technology; but the technology required to meet them is 50% more expensive than the technology required to measure radon accumulations in a slightly less accurate manner. The United States Environmental Protection Agency (EPA) does not license radon testers. However, a federal statute authorizes the EPA to advise on the accuracy of various methods of radon testing and to provide to the general public a list of testers that use methods it believes to be reasonably accurate. WeTest, a recently established Magenta firm, uses a testing method that the EPA has stated uses a testing method that the EPA has stated is reasonably accurate. WeTest is also included by the EPA on the list of testers using methods of testing it believes to be reasonably accurate. WeTest applies for a Magenta radon testing license, but its application is denied because WeTest cannot demonstrate that the method of testing for radon it uses is sufficiently accurate to meet the rigorous Magenta statutory standards. WeTest sues appropriate Magenta officials in federal court claiming that Magenta may not constitutionally exclude WeTest from performing the required radon tests in Magenta. In this suit, the court will probably rule in favor of 
WeTest, because the full faith and credit clause of the Constitution requires Magenta to respect and give effect to the action of the EPA in including WeTest on its list of testers that use reasonably accurate methods.  WeTest, because the supremacy clause of (B) WeTest, because the supremacy clause of the Constitution requires Magenta to respect and give effect to the action of the EPA in including WeTest on its list of testers that use reasonably accurate methods.  Magenta, because the federal statute and the action of the EPA in including WeTest on its list of testers that use reasonably accurate methods are not inconsistent with the more rigorous Magenta licensing requirement, and that requirement is reasonably related to a legitimate public interest.  Magenta, because radon exposure is limited to basement areas, which, by their very nature, cannot move in interstate commerce. 