Two Coaxial Circular Coils of Radius R = 15 Cm

Two coaxial circular coils of radius R = 15 cm, each carrying 4.0 A in the same direction, are positioned a distance d = 20 cm apart, as shown in the figure. Calculate the magnitude of the magnetic field halfway between the coils along the line connecting their centers. (μ₀ = 4π × 10^-7 T ∙ m/A)

A) 0.90 × 10^-5 T
B) 3.9 × 10^-5 T
C) 1.9 × 10^-5 T
D) 6.3 × 10^-5 T
E) 9.2 × 10^-5 T