[单选题]
A proton is accelerated from rest through 500 V. It enters a magnetic field fga/ lprs74b*y*d d m9q9 4xkgyp n5 1 7k8;vpuxc3nieof 0.30 T oriented perpendicular to itscnp;8 iyxv n7p 31e5uk direction of motion. Determine the radius of the path it follows.
A. $1.1 \; mm$
B. $1.1 \; cm$
C. $11 \; cm$
D. $1.1 \; m$
