magnetic field

For a charged particle performing a circular motion ,
The centripetal force is provided by the magnetic force
thus ,
the centripetal force=the magnetic force acting on the particle
mv^2/r=Bvq (where B is the magnetic flux density and q being the charge of the particle )
v=Brq/m
By v=rw
rw=Brq/m
w=Bq/m
2pi/T=Bq/m
T=2pi*m/Bq ,which is independent of v
thus, the answer is B