Answer:
A.
B. P ≈ 0
Explanation:
In order to calculate the magnetic field strength we have to use the magnetic field strength of a straight wire.
(eq. I)
B = magnetic field strength at distance d
I = current (A)
mi = represented by the greek letter μ, represents the permeability of the free space, which is: 4 × π 10^(-7) T m/A
d = distance from the wire
By replacing the values in eq I, we have the following:
(eq II)
The earth magnetic field in the surface variates from 25 to 65 microteslas. Thus:
P = Percentage from the wires/percentage of the earth
∵
∴
P ≈ 0