Two Long, Parallel Wires Are Attracted to Each Other by a Force

Two long, parallel wires are attracted to each other by a force per unit length of 160 ìN/m when they are separated by a vertical distance of 0.50 m. The current in the upper wire is 20.0 A to the right. Where on the line in the plane of the two wires does the total magnetic field equal zero?

A) 0.1 m below the upper wire
B) 0.2 m below the upper wire
C) halfway between the wires
D) 0.3 m below the upper wire