[单选题]
01.17: If 25% of a sample ofpy vx7(,tc8 sh a radioact7 9ceifg,8vdm1:z y.y w+px c)rurqlvp/4n 1 sive isotope decays in 4 hours, we would estimate r18+ ,)7f c viqnp lymxy4pz:wc9/.dr uvg1esthe sample's half life to be about
A. 1.9 hours
B. 4.0 hours
C. 8.0 hours
D. 9.6 hours
E. 13.8 hours
