A Proton, Moving in a Uniform Magnetic Field, Moves in a Circle

Multiple Choice

A proton, moving in a uniform magnetic field, moves in a circle perpendicular to the field lines and takes time T for each circle. If the proton's speed tripled, what would now be its time to go around
Each circle?

A) $T / 9$
B) $3 T$
C) $9 T$
D) $T$
E) $T / 3$