For the function f(x,y) = {x³}/{3} + xy + y , what are the critical points and their types?
A) Critical points are (0,0) and (1,-1), both are minimum points.
B) Critical points are (0,0) and (1,-1), one is a maximum and the other is a minimum.
C) Critical points are (0,0) and (1,-1), both are saddle points.
D) Critical points are (0,0) and (1,-1), one is a saddle point and the other is undecidable.
