Three Long Parallel Wires Each Carry 2 $\vec { B }$

Three long parallel wires each carry 2.0-A currents in the same direction.The wires are oriented vertically,and they pass through three of the corners of a horizontal square of side 4.0 cm.What is the magnitude of the $\vec { B }$ field at the fourth (unoccupied) corner of the square due to these wires? (μ₀ = 4π × 10^-7 T ∙ m/A)

A) 1.2 µT
B) 2.1 µT
C) 12 µT
D) 21 µT
E) 0 T