Mitch, an NRA, Sells a Building in Omaha for $1

Mitch, an NRA, sells a building in Omaha for $1 million. His basis in the building is zero for both regular tax and AMT purposes. Mitch has no other contact with the U.S. other than the ownership of the building. How much Federal income tax is due from Mitch on the sale?

A) $0, as Mitch is an NRA.
B) The amount realized times the top individual tax rate.
C) The net gain times the top capital gains tax rate.
D) The net gain taxed at the lesser of the applicable regular or AMT rates.