A singly ionized chloride ion (charge −e) moves in the horizontal plane with a velocity that is 30∘ north of east. A uniform magnetic field of magnitude B is directed straight upward. Which of the following best describes the direction of the magnetic force acting on the ion?
a) 30∘ north of west in the horizontal plane
b) 60∘ south of east in the horizontal plane
c) 60∘ north of west in the horizontal plane
d) Vertically downward