Two Parallel Conductors Are Carrying Currents in the Same Direction

Multiple Choice

Two parallel conductors are carrying currents in the same direction.The currents are non-zero and not necessarily equal.The magnitude of the magnetic field midway between them is 40 μT.If one of the currents then has its direction reversed,what is the resulting magnitude of the magnetic field midway between them?

A) a value greater than 40 μT
B) 40 μT
C) a value less than 40 μT
D) It could be any value.