A particle with charge +Q and mass m enters a magnetic field of magnitude B, existing only to the right of the boundary YZ. The direction of the motion of the particle is perpendicular to the direction of B. Let T = 2π(m/QB). The time spent by the particle in the field will be
(a) Tθ
(b) 2Tθ
(c) T (π + 2θ/2π)
(d) T (π - 2θ/2π)
