An Unusual Lightning Strike Has a Vertical Portion with a Current

Multiple Choice

An unusual lightning strike has a vertical portion with a current of −400 A downwards. The Earth's magnetic field at that location is parallel to the ground and has a magnitude of 30 μT. In N, the force exerted by the Earth's magnetic field on the 25 m-long current is

A) 0.
B) 0.012 N, East.
C) 0.012 N, West.
D) 0.30 N, West.
E) 300 N, East.