In radiative coupling, the emitter radiation field_____________?

A. Decays as 1 / R, where R is the separation distance between the emitter and the receptor
B. Decays as R, where R is the separation distance between the emitter and the receptor
C. Decays as 1 / 2 R, where R is the separation distance between the emitter and the receptor
D. Decays as 2R, where R is the separation distance between the emitter and the receptor