Consider the Following Nonlinear System

Multiple Choice

Consider the following nonlinear system:

Which of these statements is true? Select all that apply.

A) There are no isolated closed trajectories for this system.
B) For r > 0, the corresponding solution trajectories spiral outward away from r = 1 in a counterclockwise fashion.
C) For 0 < r < 1, the corresponding solution trajectories spiral toward the origin in a counterclockwise fashion.
D) The unit circle is a semistable limit cycle.
E) The unit circle is an unstable limit cycle.