B. The initial velocity has components both parallel and perpendicular to the magnetic field.
Explanation:
When a charged particle moves in a magnetic field, it experiences a force which is given by
[tex]F=qvB sin \theta[/tex]
where
q is the charge
v is the velocity of the particle
B is the strength of the magnetic field
[tex]\theta[/tex] is the angle between the directions of v and B
From this formula, it is clear that the force has only a component in the direction perpendicular to direction of the the motion of the particle. Therefore: