[单选题]
97.25: Originally there are N atofhy/b, h.6+ u6fa4xtk mfs:wxms of an un,nov;fk e9lj22uhh od( +ki 2qstable isotope. After 20 minutes, only 1/16 of them have not decayed.2(jo9iekk;qo ,d +hlfnv2 2uh What is the half life of the isotope?
A. 10 minutes
B. 5 minutes
C. 4 minutes
D. 2 minutes
E. 1 minute
