The Figure Shows a Cross Section of Three Parallel Wires

Multiple Choice

The figure shows a cross section of three parallel wires each carrying a current of 20 A.The currents in wires A and B are out of the paper,while that in wire C is into the paper.If the distance R = 5.0 mm,what is the magnitude of the force on a 2.0-m length of wire A?

A) 23 mN
B) 64 mN
C) 32 mN
D) 46 mN
E) 55 mN