BM=MN=NA,点A(1,0),B(0,1),所以M( 1 3 , 2 3 ),N( 2 3 , 1 3 ),分别代入y=xα,y=xβ得α=log 2 3 1 3 ,β=log 1 3 2 3 ,∴αβ=log 2 3 1 3 ?log 1 3 2 3 =1.故选:A.