15. Two parallel wires, 4.0 cm apart, both carry currents of 2.0 A in the same direction. What is the force per unit length of one wire on the other? (µo = 1.3 x 10-6 N. A-2) (A) 2.0 x 10-5 N/m, attractive (B) 1.1 x 10-5 N/m, attractive (C) 2.0 x 10-5 N/m, repulsive (D) 1.1 x 10-5 N/m, repulsive