Which option correctly lists the sequence of cause-and-effect steps that makes an electromagnetic wave self-sustaining in free space?
a) (i) Constant electric field → conduction current → magnetic field, (ii) Static magnetic field → constant electric field, cycles repeat indefinitely.
b) (i) Time-varying magnetic field → displacement current → electric field, (ii) Time-varying electric field → conduction current → magnetic field.
c) (i) Time-varying electric field → displacement current → magnetic field, (ii) Time-varying magnetic field → induced electric field, cycles repeat indefinitely.
d) (i) Electric field accelerates virtual charges in vacuum → current → magnetic field, (ii) Magnetic field induces e.m.f. that regenerates the current without needing field variation.