A charged particle is moving in a constant magnetic field and at some point it has its velocity vector making an acute angle with the magnetic field. The path of the particle will be

Question

$\begin {array} {1 1} (a)\;Straight\: line & \quad (b)\;ircle \\ (c)\;Helix\: with\: uniform\: pitch & \quad (d)\;Helix\: with\: non-uniform \: pitch \end {array}$