[单选题]
A cyclotron of radius 0ce0 50zarun x:*6p2emtt e. zh.k0b1 6/y xtcjfp qb6de)dav5: 25 m accelerates protons in a 1.7-T magnetic field. What is the frequ/1):6a tdbbfp j x5q6ve 0yckdency for the applied alternating voltage?
A. $0.26 \; MHz$
B. $2.6 \; MHz$
C. $26 \; MHz$
D. $260 \; MHz$