A Charged Particle Is Observed Traveling in a Circular Path $8 R$

Multiple Choice

A charged particle is observed traveling in a circular path of radius R in a uniform magnetic field. If the particle were traveling twice as fast, the radius of the circular path would be

A) $8 R$ .
B) $R / 2$ .
C) $4 R$ .
D) $R / 4$ .
E) $2 R$ .