magnetism/ college-level physics HELP ASAP

Question

positively charged particle is stationary in a constant magnetic field within a region of space. Which one of the following statements concerning the particle is true?

1. The particle will not move.
2. The particle will accelerate in the direction perpendicular to the field.
3. The particle will accelerate in the direction parallel to the field.
4. The particle will accelerate in the direction opposite to the field.
5. The particle will move with constant velocity in the direction of the field.

Answer 1

The answer is A: the particle will not move.

The force F on a particle with charge q and velocity v in a magnetic field B is

F=q*(v x B)

where x is the cross product. This means that if the velocity of the particle is zero, it experiences no force from a magnetic field.