[单选题]
The half-life of rad:tnnr;bh -xk vy9 */ sxx*lvc1ioactive iodine-137 is cs5v xztn/v(+rc6vi w; 90afu 8.0 days. How many iodine nuclei are necessary to produce an activity v ni r t/xa fcz6u95w;(svv+0cof $1.0 \; \mu Ci$?
A. $2.9 \times 10^{9}$
B. $4.6 \times 10^{9}$
C. $3.7 \times 10^{10}$
D. $7.6 \times 10^{12}$
