Which of the Following Is a Critical Point of This

Multiple Choice

Which of the following is a critical point of this nonlinear system?

Select all that apply.

A) (1, -1)
B) (-7, -7)
C) (1, 7)
D) (-1, 1)
E) (-1, 7)
F) (-7, 7)
G) (7, 7)
H) (0, 0)