B.) Inversion.
I'm not quite sure, so might wanna double check, but I think that's correct. Hope I helped, if not I apologize.
Answer:
Boundary of the heliosphere
Explanation:
It is the spherical region around the sun that is filled with solar magnetic fields.The shape of the heliopause fluctuates an is influenced by a wind of interstellar gas caused by the suns motion through space.
