Step-by-step explanation:
The magnetic force acting on a charged particle when placed in a magnetic field is given by :


is the angle between v and B.
If means that if the angle between v and B is 0 degrees or both are acting in same direction, then magnetic force is equal to 0.
Here, a charge is moving in a magnetic field that points to the left. Hence, for a charge particle that experiences no magnetic force, the charge must move in the left direction such that they move parallel to each other.