A horizontal overhead power line is at a height of 4 m from the ground and carries a current of 100 A from east to west. The magnetic field directly below it on the ground is $$(\mu_0 = 4\pi \times 10^{-7}\ T\ m\ A^{-1})$$

A

$$2.5 \times 10^{-7}$$ T southward

B

$$5 \times 10^{-6}$$ T northward

C

$$5 \times 10^{-6}$$ T southward

D

$$2.5 \times 10^{-7}$$ T northward