At a point P on the curve given implicitly by F(x,y)=0, it is known that dxdy=0 and dx2d2y<0. Which of the following best describes the behavior of the curve at P?
a) P is a saddle point (a point of inflection) on the curve.
b) P is a local maximum of y with respect to x. (correct)
c) The information given is insufficient to classify P.
d) P is a local minimum of y with respect to x.