From Ampere’s circuital law for a long straight wire of circular cross-section carrying a steady current, the variation of magnetic field in the inside and outside region of the wire is:

1. A
   Uniform and remains constant for both the regions
2. B
   A linearly increasing function of distance up to the boundary and then linearly decreasing outside
3. C
   A linearly increasing function of distance $r$ up to the boundary and then decreasing with $1/r$ dependence outside
4. D
   A linearly decreasing function of distance up to the boundary and then linearly increasing outside