If the partial differential equation
$$
(x+2) \frac{\partial^2 u}{\partial x^2}+2(x+y) \frac{\partial^2 u}{\partial x \partial y}+2(y-1) \frac{\partial^2 u}{\partial y^2}-3 y^2 \frac{\partial u}{\partial y}=0
$$
is parabolic on the circle $(x-a)^2+(y-b)^2=r^2$, then the values of $a, b$ and $r$ are given by
- $a=1, b=2, r=1$
- $a=-1, b=2, r=1$
- $a=1, b=-2, r=1$
- $a=-1, b=-2, r=1$
