According to Ampere’s Law:
Where,

B is the magnetic field,

dl is the current element,

μ₀ is the permeability of free space

i is the current flowing in the conductor

Magnetic field outside the cable: B = B_I+B_O
B_I and B_O are the magnetic field of the inner conductor and outer cable respectively.
Due to wire,
R is the radius of the wire.


Thus, option (A) is the correct option.

Magnetic field inside the inner conductor:

∮B. dl =μ_o I (I=0(inside the wire))

Magnetic field between the two conductors and inside the outer conductor.

∮B. dl =μ_o I

On integrating the length element over the complete loop, we get dl= 2π r

B.2π r=μ_o I

On solving the above equation for B, we get

Thus, option A and B is the correct option.