The MA is 6! Hope This Helps!
To develop this problem it is necessary to apply the concepts related to a magnetic field in spheres.
By definition we know that the magnetic field in a sphere can be described as

Where,
a = Radius
z = Distance to the magnetic field
I = Current
Permeability constant in free space
Our values are given as
diameter of the sphere then,

Thus z = a



Re-arrange to find I,



Therefore the current at the pole of this sphere is 
Answer: Current needed, mA 20 Voltage needed, V AC 6
Explanation: An electric gradient (or field) can exist that is analogous to the situation described above for step and touch potentials. The situation is more complex to analyze in the water because a person in the water assumes different postures and orientations in 3 dimensions (up, down, and sideways—north, south, east, and west). The transthoracic and translimb voltages will vary as the person moves in relation to the orientation (direction) of the electric field.