I=P4πr2At a large distance r from a radio antenna, the intensity of the radio signal I is related to the power of the signal P by the formula above.For the same signal emitted by a radio antenna, Observer A measures its intensity to be 16 times the intensity measured by Observer B. The distance of Observer A from the radio antenna is what fraction of the distance of Observer B from the radio antenna?
A. 1/4
B. 1/16
C. 1/64
D. 1/256
