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Consider the following autonomous system

$\cfrac{dx}{dt}=1-xy$$\cfrac{dy}{dt}=x-y^3$

About the critical points, which of the following is wrong?

$(1,1)$ is a critical point.

$(1,-1)$ is a critical point.

$(-1, -1)$ is a critical point.

$(-1,1)$ is not a critical point.