Two Long Parallel Wires Carry Unequal Currents in Opposite Directions $\mu$

Multiple Choice

Two long parallel wires carry unequal currents in opposite directions.The ratio of the currents is 3 to 1.The magnitude of the magnetic field at a point in the plane of the wires and 10 cm from each wire is 4.0 $\mu$ T.What is the larger of the two currents?

A) 0.5 A
B) 1.0 A
C) 1.5 A
D) 2.0 A
E) 3.0 A