Iodine - 131 Is a Radionuclide That Is Frequently Used

Iodine - 131 is a radionuclide that is frequently used in nuclear medicine. Among other things, it is used to detect fluid buildup in the brain. The half-life of iodine - 131 is 8.0 days. After introducing this radionuclide to a patient, if only 1/16^th of the original sample remains, how many days have expired?

A) 0.50 days
B) 2 days
C) 7.5 days
D) 24 days
E) 32 days