The United States Department of the Interior granted Concessionaire the food and drink concession in a federal park located in the state of New Senora. Concessionaire operated his concession out of federally owned facilities in the park. The federal statute authorizing the Interior Department to grant such concessions provided that the grantees would pay only a nominal rental for use of these federal facilities because of the great benefit their concessions would provide to the people of the United States. The legislature of the state of New Senora enacted a statute imposing an occupancy tax on the occupants of real estate within that state that is not subject to state real estate taxes. The statute was intended to equalize the state tax burden on such occupants with that on people occupying real estate that is subject to state real estate taxes. Pursuant to that statute, the New Senora Department of Revenue attempted to collect the state occupancy tax from Concessionaire because the federal facilities occupied by Concessionaire were not subject to state real estate taxes. Concessionaire sued to invalidate the state occupancy tax as applied to him. The strongest ground upon which Concessionaire could challenge the occupancy tax is that it violates the 
commerce clause by unduly burdening the interstate tourist trade. privileges and immunities clause of the Fourteenth Amendment by interfering with the fundamental right to do business on federal property. equal protection of the laws clause of the Fourteenth Amendment because the tax treats him less favorably than federal concessionaires in other states who do not have to pay such occupancy taxes. supremacy clause of Article VI and the federal statute authorizing such concessions.