Consider the following familiar system in polar coordinates. Let D be the disk. Is D an invariant set?

A) Yes, D is an invariant set.
B) No, D is not an invariant set.
C) It depends on the specific system and its dynamics.
Does D attract an open set of initial conditions?
A) Yes, D attracts an open set of initial conditions.
B) No,
D does not attract an open set of initial conditions.
C) It depends on the specific system and its attractor properties.