[单选题]
A cyclotron operates at 10 MHz. What magnetic field is-ikbgi2n v2 ffv00)57djqklvsh/pw 9 5p0b nj needed to accelerate pro7k g nd v-9 i50qvjjlwbfv0k)2n5bpfh s/0ip2ng1)a fidp3vav :c)e8ton:3vc8 gn)pea)fd1 i avs?
A. $0.12 \; T$
B. $0.25 \; T$
C. $0.66 \; T$
D. $1.5 \; T$
