A uniform and constant magnetic field $$B = \hat zB$$  exists in the $$\overrightarrow z $$ direction in vacuum. A particle of mass m with a small charge q is introduced into this region with an initial velocity $$v = \hat x{v_x} + \hat z{v_z}.$$   Given that B, m, q, v_x and v_z are all non-zero. Which one of the following describes the eventual trajectory of the particle?