单项选择题

已知函数z=f(x,y)满足
,f x (1,y)=y+1,f(1,y)=y+2,则f(x,y)=
  • A.x2+(y-1)x+2.
  • B.x2+(y+1)x+2.
  • C.x2+(y-1)x-2.
  • D.x2+x(y+1)-2.