A Charged Particle (M = 5 $\mu$ C) Moves Horizontally at a Constant Speed of 30 Km/s

Multiple Choice

A charged particle (m = 5.0 g, q = -70 $\mu$ C) moves horizontally at a constant speed of 30 km/s in a region where the free fall gravitational acceleration is 9.8 m/s2 downward, the electric field is 700 N/C upward, and the magnetic field is perpendicular to the velocity of the particle.What is the magnitude of the magnetic field in this region?

A) 47 mT
B) zero
C) 23 mT
D) 35 mT
E) 12 mT