A Positively Charged Ping Pong Ball Is Sitting Stationary on the Floor

Multiple Choice

A positively charged ping pong ball is sitting stationary on the floor in the center of a room. There is also a constant, uniform magnetic field in the room that points toward the ceiling. If I now start the ball rolling toward the back of the room, the resultant motion of the ball, as observed from the ceiling, will be

A) a diagonal straight line toward the left back corner of the room.
B) a diagonal straight line toward the right back corner of the room.
C) a horizontal, clockwise circle.
D) a horizontal, counterclockwise circle.
E) a straight line in the original direction of motion.