which of the following formoalas is representation of the inverse square law and may be used to determine x-ray intensity at different distances

which of the following formoalas is representation of the inverse square law and may be used to determine x-ray intensity at different distances?
a.I/I = D/D
B. I/I = D/D
C. KVP/ KVP = D/D
D. KVP /KVP = D/D