[单选题]
08.47: A radioactive sayzcw3z ;m- 50tvy8rrlmple decays with a half-life of 2.0pba3 9(+vbaoo yr. Approximately how much time mustoba(p 9+ ov3ba pass so that only 1/3 of the original sample remains?
A. 6.0 yr
B. 3.4 yr
C. 3.2 yr
D. 3.0 yr
E. 2. 8 yr